So it is not quite possible to have a "monoecious flower" because the definition of monoecious applies to entire plants. Monoecious (which means "one household" or one ecos) plants produce flowers that are unisexual - male and female - and both kinds of flowers are found on the same individual plant. This contrasts with dioecious plants, which also bear unisexual flowers. But a dioecious plant keeps two households, and an individual plant produces only male or female flowers. The reason we bother to distinguish these habits in the first place is that most plants produce flowers that are perfect: a single flower has both male (the pollen-producing stamens) and female (egg-producing pistils) parts.
The timeliness in talking about a monoecious flower relates to flowering of the Titan Arum, Amorphophallus titanum. One of the many Titan Arum plants at The Huntington is coming into flower; people call it the Stinky Plant. People also call it the largest flower in the world because it certainly looks like a single flower. But to a botanist the Titan Arum is really a massive and glorious cluster of flowers, an inflorescence, that looks like a single flower. Every plant in the arum family does this, and all follow a similar pattern; tiny flowers are clustered along a narrow stem called the spadix. The flowers may be perfect, having both stamens and pistils. But in many, pistillate flowers are produced along one zone of the axis while staminate flowers grow in a separate zone. Surrounding the spadix is an impressive, petal-like leafy bract called a spathe.
In some members of the arum family, like Philodendron, the spathe completely surrounds the spadix - opening only at the very tip. In others, like Spathiphyllum and Anthurium, the spathe doesn't surround the spadix at all. A whole bunch of aroids have a spathe that surrounds the base of the spadix, and then opens up entirely, making a hood. This is what plants in the genus Arum do.
The spathe may lack a hood, simply cupping around the spadix. This is the story for the most spectacular of the arums, the lowland tropical Titan Arum. And everything about this plant seems extraordinary, from seed to flower. When a seed germinates, it makes a simple underground stem called a corm, and a single leaf. Seasonally, the leaf withers and falls off; with a new growth season the enlarged corm produces another single leaf, but much larger. Several cycles of growth yield an increasing larger corm and leaf, to the point that the single leaf grows to a height of over 8 feet, with a spread of over 6 feet. The petiole of the leaf is so large that you can't wrap your hands completely around it.
At some point the plant has reached a sufficient size to flower. When that happens, the cycle is interrupted. Instead of another single leaf, the flowering stem is produced, a massive and beautiful elaboration. As soon as the flowering stalk breaks the surface of the soil, it is clearly not the normal leaf. Within just a few weeks, the inflorescence (the spadix) grows to 4-5 feet tall, tightly enrobed by the spathe. At maturity, the spathe unfolds, forming a flared vase that is deep maroon purple on its upper surface. Projecting from and presiding over the vase is the inflated spadix - but the visible portion is sterile. The male and female flowers are clustered in zones down inside the vase-like portion of the spathe, but they do not mature on the same day.
The female flowers mature first, and are receptive before the pollen is ready. Very soon after that, the male flowers mature and release the pollen. In nature, the inflorescence attracts flies, which arrive and crawl over the flowers. If the flies already have visited a Titan Arum, they may well come already covered with pollen, and therefore pollinate the female flowers. If not, then perhaps they will leave the Titan Arum with pollen which is carried to the next flower they visit. But what do the flies get out of this?
Well not much. It's a false alarm for them. Flies come to the Titan Arum expecting to find rotting meat. The spathe even has a dark flesh color, but the color is not what draws flies. It is the fragrance that draws flies; the alluring, decomposing protein aroma of rotting flesh. People can smell it also, but we are generally repelled by odors that many flies find irresistible. So the flies come, and they hang around. When the party is over, the flies leave. Though completely duped by the flower, the flies do not hesitate to visit a second or third if it is available.
After just a few days, the entire structure collapses in a sodden mass. If pollination and fertilization were successful, then seed begin to form in bright orange-red fruit, and a new generation is ready. But the parent plant is not especially caput. As long as the corm is intact, the vegetative cycle begins anew. Once the corm mass is restored, then the plant might bloom again. A plant that bloomed at The Huntington in 1999 flowered again in 2002, and persists to this day, slowly gaining leaf size from one growth cycle to the next.
Saturday, June 6, 2009
Sunday, May 31, 2009
Being Green
Green. Why has green become the byword for things sustainable? And what is green - origin, function, symbol?
Green is on all of the color charts; it is the complement of red - when you focus on a green object and then close your eyes, the residual image glows red.
Green is at the center of the human visual spectrum - we detect and differentiate tens of thousands (even millions) of greens. In physics, that means we are most aware of impacts on light waves around 570 nanometers, at the center of our visual span, which runs from violet, at about 380 nm, to far red, at 750 nm.
This is not just the visible spectrum of light, it is also the biologically active spectrum. Wavelengths of light that are shorter than 380 nm border on the ultraviolet; they are more energetic than longer wavelengths and can be harmful to organic molecules, denaturing and destroying them. Wavelengths longer than 750 nm are increasingly infrared, less energetic than most visible light, playing out as heat. Light in the visual spectrum has the useful ability to affect organic reaction centers, to cause temporary, non-destructive activity that can drive chemical change.
Thus photosynthesis. The world we perceive from our green-centric viewpoint is powered through the blue and red light that drives photosynthesis. When blue and red light strikes photosynthetic reaction centers, electrons are energized, then lost into a chain of events, transported through a series of reactions that harvest the extra energy, storing it in chemical bonds. This newly bound-up chemical energy can be used at a later point to bond carbon atoms into chains that yield sugars and eventually the myriad of other organic compounds that make a plant.
But in passing along those electrons, the photosynthetic reaction center suffers an ongoing need for other electrons to reset the photochemical mechanism. Those replacement electrons, in effect, come from a powerful capacity to disassemble molecules of water. The photosynthetic apparatus is practically unique in its capacity to split water into oxygen, protons (hydrogen), and electrons. The oxygen we breathe was freed from water during ancient and on-going acts of photosynthesis.
The direct and curious relationship, then, between water and green is the capture of light during photosynthesis, from which there are by-products. Oxygen is left over from the water that was split. Green light is left over when the red and blue light are taken from the spectrum (though it is not this simple; there are other light-absorbing compounds involved.)
So plants are green because they do not use green light. Our world is green because green, photosynthesizing plants are the basis for life on Earth. How convenient! Green describes the range of colors we perceive best. And that all makes sense because our vision depends on non-destructive light-driven reactions. So it is no surprise that our vision and the photosynthetic process depend on the same special spectrum of radiation - visible light.
To flash red is to send an alert, to call a stop, to wave a flag. A green light signals the coast is clear, an open field. Green is our comfort color. Green is fresh, it is crisp lettuce. Green is living, like lawn or trees. So green has become the color associated with ecology, and ecology has become synonymous with environmental protection, which we associate with stewardship and sustainability. Thus green has become the color of sustainability, about which we have much to learn. And as Kermit tells us, it isn't easy being green.
Green is on all of the color charts; it is the complement of red - when you focus on a green object and then close your eyes, the residual image glows red.
Green is at the center of the human visual spectrum - we detect and differentiate tens of thousands (even millions) of greens. In physics, that means we are most aware of impacts on light waves around 570 nanometers, at the center of our visual span, which runs from violet, at about 380 nm, to far red, at 750 nm.
This is not just the visible spectrum of light, it is also the biologically active spectrum. Wavelengths of light that are shorter than 380 nm border on the ultraviolet; they are more energetic than longer wavelengths and can be harmful to organic molecules, denaturing and destroying them. Wavelengths longer than 750 nm are increasingly infrared, less energetic than most visible light, playing out as heat. Light in the visual spectrum has the useful ability to affect organic reaction centers, to cause temporary, non-destructive activity that can drive chemical change.
Thus photosynthesis. The world we perceive from our green-centric viewpoint is powered through the blue and red light that drives photosynthesis. When blue and red light strikes photosynthetic reaction centers, electrons are energized, then lost into a chain of events, transported through a series of reactions that harvest the extra energy, storing it in chemical bonds. This newly bound-up chemical energy can be used at a later point to bond carbon atoms into chains that yield sugars and eventually the myriad of other organic compounds that make a plant.
But in passing along those electrons, the photosynthetic reaction center suffers an ongoing need for other electrons to reset the photochemical mechanism. Those replacement electrons, in effect, come from a powerful capacity to disassemble molecules of water. The photosynthetic apparatus is practically unique in its capacity to split water into oxygen, protons (hydrogen), and electrons. The oxygen we breathe was freed from water during ancient and on-going acts of photosynthesis.
The direct and curious relationship, then, between water and green is the capture of light during photosynthesis, from which there are by-products. Oxygen is left over from the water that was split. Green light is left over when the red and blue light are taken from the spectrum (though it is not this simple; there are other light-absorbing compounds involved.)
So plants are green because they do not use green light. Our world is green because green, photosynthesizing plants are the basis for life on Earth. How convenient! Green describes the range of colors we perceive best. And that all makes sense because our vision depends on non-destructive light-driven reactions. So it is no surprise that our vision and the photosynthetic process depend on the same special spectrum of radiation - visible light.
To flash red is to send an alert, to call a stop, to wave a flag. A green light signals the coast is clear, an open field. Green is our comfort color. Green is fresh, it is crisp lettuce. Green is living, like lawn or trees. So green has become the color associated with ecology, and ecology has become synonymous with environmental protection, which we associate with stewardship and sustainability. Thus green has become the color of sustainability, about which we have much to learn. And as Kermit tells us, it isn't easy being green.
Sunday, May 24, 2009
Another Byt of Linnaeus
I introduced Linnaeus to the blog on his birthday, but I just can't be finished with him. His sexual system for organizing plants seems strangely sexist - the first slice at organization is based on stamens, the male parts. That isn't totally because science in the mid-1700's was a man's world, but there is a touch of that. Botanists always knew where seed were formed, and I guess the pistil and ovary had been given female associations. But Vaillant, in his 1717 lecture on the structure of flowers, was adamant about the noble role of pollen. Previously denegrated as worthless it was elevated by the new understanding that pollen is the male, it provides the sperm that brings life to an otherwise sterile egg. Linnaeus had grown up scientifically on Vaillant's lecture, and was charged up with the idea that anthers produce sperm for sexual reproduction. Now there were guys involved - the stamens - a new concept that seemed to stir the loins.
Anthers are so easily visible in flowers, and can usually be deciphered without slicing and dicing the parts. So given the new-found male pride in these now noble parts, no surprise that Linnaeus's system separates flowers based on the number and arrangement of stamens. And of course any ideological divisions bring artificial results, making for strange bedfellows. Any group of plants that has five stamens in their flowers will end up grouped together - regardless how very different they might be otherwise. And two plants that naturally should be grouped together would be pigeonholed in different places if one had five stamens and the other one ten.
Thumbing through Species Plantarum (1753), we can see some of the issues:
Class 1 - Monandria (One Stamen): Canna, Costus
Class 2 - Diandria (Two Stamens): Jasminum, Ligustrum, Olea, Syringa, Veronica, Justicia, Pinguicula, Verbena, Rosmarinus, Salvia, Piper
Class 3 - Triandria (Three Stamens): Ixia, Gladiolus, Commelina, Xyris, Cyperus, Scirpus, Saccharum, Panicum, Poa, Festuca, Arundo, Triticum, Eriocaulon
Class 4 - Tetrandria (Four Stamens): Leucadendron, Protea, Cephalanthus, Scabiosa, Houstonia, Galium, Buddleja, Plantago, Cornus, Trapa, Cuscuta, Ilex, Potamogeton
Class 5 - Pentadria (Five Stamens): Heliotropium, Myosotis, Cynoglossum, Pulmanaria, Borago, Echium, Primula, Azalea, Plumbago, Phlox, Convolvulus, Ipomoea, Campanula, Nicotiana, Physalis, Solanum, Ceanothus, Celastrus, Euonymus, Ribes, Hedera, Vitis, Vinca, Nerium, Asclepius, Chenopodium, Gentiana, Eryngium, Apium, Rhus, Viburnum, Turnera, Statice, Linum, Drosera, Crassula
Class 6 - Hexandria (Six Stamens): Bromelia, Tradescantia, Narcissus, Crinum, Amaryllis, Allium, Lilium, Tulipa, Ornithogalum, Asparagus, Hyacinthus, Aloe, Hemerocallis, Juncus, Oryza, Rumex, Trillium, Colchicum
Class 7 - Heptandria (Seven Stamens): Aesculus
Class 8 - Octandria (Eight Stamens): Tropaeolum, Rhexis, Oenothera, Gaura, Vaccinium, Erica, Daphne, Polygonum, Sapindus, Paris
Class 9 - Enneandria (Nine Stamens): Laurus, Rheum
Class 10 - Decandria (Ten Stamens): Sophora, Cassia, Schinus, Melastoma, Kalmia, Rhododendron, Arbutus, Clethra, Pyrola, Hydrangea, Saxifraga, Gypsophila, Saponarai, Dianthus, Silene, Lychnis, Oxalis, Phytolacca
Class 11 - Dodecandria (Twelve Stamens): Asarum, Rhizophora, Styrax, Portulaca, Euphorbia
Class 12 - Icosandria (Twenty Stamens): Cactus, Psidium, Myrtus, Prunus, Mesembryanthemum, Spiraea, Rosa, Rubus, Potentilla
Class 13 - Polyandria (Numerous Stamens): Papaver, Sarracenia, Clusia, Bombax, Bixa, Mimosa, Cistus, Delphinium, Nigella, Magnolia, Annona, Anemone, Ranunculus
Class 14 - Didynamia (Four Stamens in two pairs of different lengths): Ajuga, Teucrium, Nepeta, Lavandula, Stachys, Phlomis, Dracocephalum, Ocimum, Scutellaria, Pedicularis, Antirrhinum, Scrophularia, Digitalis, Bignonia, Lantana, Duranta, Acanthus, Vitex
Class 15 - Tetradynamia (Six stamens, two shorter than the other four): Draba, Iberis, Alyssum, Cardamine, Cheiranthus, Arabis, Brassica, Cleome
Class 16 - Monadelphia (Stamens bound together by their filaments): Hermannia, Geranium, Sida, Althea, Alcea, Malva, Gossypium, Hibiscus, Stewartia, Camellia
Class 17 - Diadelphia (Stamens bound by filaments, but into two bundles or sheaths): Fumaria, Polygala, Genista, Robinia, Pisum, Lathyrus, Vicia, Clitoria, Glycine, Astragalus, Trifolium, Lotus, Medicago
Class 18 - Polydelphia (Stamens bound by filaments into five bundles): Theobroma, Citrus, Hypericum
Class 19 - Syngenesia (Stamens united at the anthers): Tragopogon, Sonchus, Lactuca, Carduus, Eupatorium, Ageratum, Santolina, Artemisia, Gnaphalium, Erigeron, Senecio, Solidago, Inula, Achillea, Chrysanthemum, Helianthus, Rudbeckia, Centauria, Calendula, Osteospermum, Lobelia, Viola, Impatiens
Class 20 - Gynandria (Feminine males, Stamen combined with style and stigma): Orchis, Cypripedium, Epidendrum, Sisyrinchium, Nepenthes, Passiflora, Aristolochia, Pistia, Grewia, Arum, Arum, Dracontium, Calla, Pothos
Class 21 - Monoecia (Monoecious plants): Callitriche, Lemna, Typha, Carex, Ambrosia, Amaranthus, Quercus, Fagus, Platanus, Liquidambar, Pinus, Cupressus, Acalypha, Jatropha, Ricinus, Sterculia, Cucurbita
Class 22 - Dioecia (Dioecious plants): Najas, Salix, Myrica, Spinacia, Cannabis, Humulus, Smilax, Dioscorea, Populus, Carica, Juniperus, Taxus, Ruscus
Class 23 - Polygamia: Musa, Celtis, Andropogon, Acer, Begonia, Fraxinus, Diospyros, Nyssa, Panax, Ficus
Class 24 - Cryptogamia (Flowers not readily visible): Equisetum, Ophioglossum, Osmunda, Pteris, Blechnum, Asplenium, Polypodium, Adiantum, Lycopodium, Sphagnum, Polytrichum, Mnium, Bryum, Marchantia, Riccia, Anthoceros, Lichen, Ulva, Agaricus, Peziza
Wow! If you take a few minutes to read through the groupings, it is clear the system creates a lot of curious combinations. Many things work pretty well; the orchids are together, so are the mustards. The daisies (composites) are together, but they fall out, along with the lobelias, in their own funny group - plants that have stamens united at the anther. Since all of the composites have five stamens, they could have been placed in Pentandria, but almost certainly Linnaeus enjoyed this clever method of separating them from other plants that do not produce flowers in heads. It is also interesting that Linnaeus groups the gymnosperms in with the flowering plants; pines are right after the oaks. And he includes Ilex in Tetrandia, even though the other dioecious plants are in Dioecia. Clearly, Linnaeus took the license to split whatever hairs he needed to split to make things work out; the system was not without ambiguity.
But what a hoot. Just as an aspiring artist might paint in a gallery, copying a great master in order to discover the techniques involved in creating miraculous effects, we can use Linnaeus's system in order to step into his mind. It is a very orderly, personality-ridden place.
Anthers are so easily visible in flowers, and can usually be deciphered without slicing and dicing the parts. So given the new-found male pride in these now noble parts, no surprise that Linnaeus's system separates flowers based on the number and arrangement of stamens. And of course any ideological divisions bring artificial results, making for strange bedfellows. Any group of plants that has five stamens in their flowers will end up grouped together - regardless how very different they might be otherwise. And two plants that naturally should be grouped together would be pigeonholed in different places if one had five stamens and the other one ten.
Thumbing through Species Plantarum (1753), we can see some of the issues:
Class 1 - Monandria (One Stamen): Canna, Costus
Class 2 - Diandria (Two Stamens): Jasminum, Ligustrum, Olea, Syringa, Veronica, Justicia, Pinguicula, Verbena, Rosmarinus, Salvia, Piper
Class 3 - Triandria (Three Stamens): Ixia, Gladiolus, Commelina, Xyris, Cyperus, Scirpus, Saccharum, Panicum, Poa, Festuca, Arundo, Triticum, Eriocaulon
Class 4 - Tetrandria (Four Stamens): Leucadendron, Protea, Cephalanthus, Scabiosa, Houstonia, Galium, Buddleja, Plantago, Cornus, Trapa, Cuscuta, Ilex, Potamogeton
Class 5 - Pentadria (Five Stamens): Heliotropium, Myosotis, Cynoglossum, Pulmanaria, Borago, Echium, Primula, Azalea, Plumbago, Phlox, Convolvulus, Ipomoea, Campanula, Nicotiana, Physalis, Solanum, Ceanothus, Celastrus, Euonymus, Ribes, Hedera, Vitis, Vinca, Nerium, Asclepius, Chenopodium, Gentiana, Eryngium, Apium, Rhus, Viburnum, Turnera, Statice, Linum, Drosera, Crassula
Class 6 - Hexandria (Six Stamens): Bromelia, Tradescantia, Narcissus, Crinum, Amaryllis, Allium, Lilium, Tulipa, Ornithogalum, Asparagus, Hyacinthus, Aloe, Hemerocallis, Juncus, Oryza, Rumex, Trillium, Colchicum
Class 7 - Heptandria (Seven Stamens): Aesculus
Class 8 - Octandria (Eight Stamens): Tropaeolum, Rhexis, Oenothera, Gaura, Vaccinium, Erica, Daphne, Polygonum, Sapindus, Paris
Class 9 - Enneandria (Nine Stamens): Laurus, Rheum
Class 10 - Decandria (Ten Stamens): Sophora, Cassia, Schinus, Melastoma, Kalmia, Rhododendron, Arbutus, Clethra, Pyrola, Hydrangea, Saxifraga, Gypsophila, Saponarai, Dianthus, Silene, Lychnis, Oxalis, Phytolacca
Class 11 - Dodecandria (Twelve Stamens): Asarum, Rhizophora, Styrax, Portulaca, Euphorbia
Class 12 - Icosandria (Twenty Stamens): Cactus, Psidium, Myrtus, Prunus, Mesembryanthemum, Spiraea, Rosa, Rubus, Potentilla
Class 13 - Polyandria (Numerous Stamens): Papaver, Sarracenia, Clusia, Bombax, Bixa, Mimosa, Cistus, Delphinium, Nigella, Magnolia, Annona, Anemone, Ranunculus
Class 14 - Didynamia (Four Stamens in two pairs of different lengths): Ajuga, Teucrium, Nepeta, Lavandula, Stachys, Phlomis, Dracocephalum, Ocimum, Scutellaria, Pedicularis, Antirrhinum, Scrophularia, Digitalis, Bignonia, Lantana, Duranta, Acanthus, Vitex
Class 15 - Tetradynamia (Six stamens, two shorter than the other four): Draba, Iberis, Alyssum, Cardamine, Cheiranthus, Arabis, Brassica, Cleome
Class 16 - Monadelphia (Stamens bound together by their filaments): Hermannia, Geranium, Sida, Althea, Alcea, Malva, Gossypium, Hibiscus, Stewartia, Camellia
Class 17 - Diadelphia (Stamens bound by filaments, but into two bundles or sheaths): Fumaria, Polygala, Genista, Robinia, Pisum, Lathyrus, Vicia, Clitoria, Glycine, Astragalus, Trifolium, Lotus, Medicago
Class 18 - Polydelphia (Stamens bound by filaments into five bundles): Theobroma, Citrus, Hypericum
Class 19 - Syngenesia (Stamens united at the anthers): Tragopogon, Sonchus, Lactuca, Carduus, Eupatorium, Ageratum, Santolina, Artemisia, Gnaphalium, Erigeron, Senecio, Solidago, Inula, Achillea, Chrysanthemum, Helianthus, Rudbeckia, Centauria, Calendula, Osteospermum, Lobelia, Viola, Impatiens
Class 20 - Gynandria (Feminine males, Stamen combined with style and stigma): Orchis, Cypripedium, Epidendrum, Sisyrinchium, Nepenthes, Passiflora, Aristolochia, Pistia, Grewia, Arum, Arum, Dracontium, Calla, Pothos
Class 21 - Monoecia (Monoecious plants): Callitriche, Lemna, Typha, Carex, Ambrosia, Amaranthus, Quercus, Fagus, Platanus, Liquidambar, Pinus, Cupressus, Acalypha, Jatropha, Ricinus, Sterculia, Cucurbita
Class 22 - Dioecia (Dioecious plants): Najas, Salix, Myrica, Spinacia, Cannabis, Humulus, Smilax, Dioscorea, Populus, Carica, Juniperus, Taxus, Ruscus
Class 23 - Polygamia: Musa, Celtis, Andropogon, Acer, Begonia, Fraxinus, Diospyros, Nyssa, Panax, Ficus
Class 24 - Cryptogamia (Flowers not readily visible): Equisetum, Ophioglossum, Osmunda, Pteris, Blechnum, Asplenium, Polypodium, Adiantum, Lycopodium, Sphagnum, Polytrichum, Mnium, Bryum, Marchantia, Riccia, Anthoceros, Lichen, Ulva, Agaricus, Peziza
Wow! If you take a few minutes to read through the groupings, it is clear the system creates a lot of curious combinations. Many things work pretty well; the orchids are together, so are the mustards. The daisies (composites) are together, but they fall out, along with the lobelias, in their own funny group - plants that have stamens united at the anther. Since all of the composites have five stamens, they could have been placed in Pentandria, but almost certainly Linnaeus enjoyed this clever method of separating them from other plants that do not produce flowers in heads. It is also interesting that Linnaeus groups the gymnosperms in with the flowering plants; pines are right after the oaks. And he includes Ilex in Tetrandia, even though the other dioecious plants are in Dioecia. Clearly, Linnaeus took the license to split whatever hairs he needed to split to make things work out; the system was not without ambiguity.
But what a hoot. Just as an aspiring artist might paint in a gallery, copying a great master in order to discover the techniques involved in creating miraculous effects, we can use Linnaeus's system in order to step into his mind. It is a very orderly, personality-ridden place.
Saturday, May 23, 2009
Law and Order in the Plant World
Today is the 302nd anniversary of Linnaeus's birth. His is a curious legacy - revered and derided - remembered and forgotten - contemporary and anachronistic. Most of today's botanists regard him as a towering fossil; we know his L. marks thousands of plant names as part of the Linnaean foundation on which all modern plant names are based. We also know that many modern botanists are annoyed by the linearity, order, and equivalence implied in this genus-species system we inherit. Evolution has not been so complicit with human attempts to pigeon-hole the whole of creation; as Harold Bold often said: "Nature mocks at human categories."
And it was categorization that Linnaeus was all about. Today's significant holdover from Linnaeus's work is his consolidation of the binomial system of nomenclature. Linnaeus systematically brought every available plant into compliance with his way of naming and categorizing. The simplicity and thoroughness with which Linnaeus applied his way of naming plants proved of immediate and international value, sweeping away the awkward and forgetable. Today, through international agreement, we base the Code of Botanical Nomenclature on his 1753 Species Plantarum.
But for Linnaeus's contemporaries, most of whom idolized him, the immediate value of his publications was the way he organized plants. Linnaeus created a straight-forward method of grouping plants, a system that was easily memorized and utilized. For the first time in plant studies, anyone could study a new plant and know where to file it away - that is, how to classify the plant.
As a young man, Linnaeus had fallen as a thrall of sex, or more accurately, he was among the first generation of botanists who came to study plants with the awareness that seed are the fallout of sexual reproduction. Only a few years before his birth had it been made clear that pollen is the male generative force, analagous to human sperm. Linnaeaus took that fresh concept and ran with it. It was obvious to him that reproduction was crucial to preservation of every species, and the salient characteristics of reproductive organs should be directly correlated with the definition or nature of each different species. The result was his sexual system of classifying plants. Plant genera (and therefore the included species) could be grouped into Classes based on numbers and character of stamens, and within the Classes, into Orders based on the numbers and characteristics of pistils or further information on stamens.
The popularity of the sexual system of classifying plants was short-lived however. Within just a few years of Linnaeus's death, botanists published systems that grouped genera into families that seemed more "natural" - families that reflected the natural affinities of different groups of plants - affinities that would be considered ancestral and evolutionary a century later. So we are left with the binomial system of nomenclature as the residual legacy of Linnaeus's work.
But not so fast. In celebration of Linnaeus's 300th birthday two years ago, I decided it would be fun to attempt organizing a few salons that replicated the experience people would have had with Linnaeus's methods. I pulled out his simple system, assembled groups of people, and worked with the students through many plant samples. What a revelation. Of course there was no way we discovered that Linnaeus's sexual system has anything to say about how plants should be grouped or classified. What we did learn was how quickly his system cut through the mystery of a new plant. No wonder Linnaeus loved his method. He studied thousands of different kinds of plants; the sexual system represents the life-experience of one of the most brilliant field-botanists who ever lived. In using the sexual system to guide our study of many different plants at a single setting, we stepped right into Linnaeus's times and challenges. His system worked, quickly and intelligibly. It proved to be a great teaching method, bringing novices quickly into an appreciation of plant structure and diversity. Working through flowers from Linnaeus's perspective is wonderfully enlightening, engaging, and worthwhile.
But that doesn't mean there are publishable results. The system has serious limits. It gets you to a place in a list or chart, but it doesn't reckon on today's reality - the sheer number of different kinds of plants we have come to understand there are and have been on Earth. Linnaeus's system suggests a matrix of potential structural combinations, which would mean our discovery of plants would have yielded less than 50,000 kinds. He thought all the world's plants would be known in short order. That did not happen, and with over 250,000 accepted species, we continue to add new kinds. And, honestly, there is nothing that Linnaeus's system brings to the table in a contemporary understanding of plant affinities or evolution.
But for students who want to learn more plants, and more about plants, Linnaeus's methods have much to offer. Following his system gives the student of plants access to Linnaeus's approach to making sense of the great range of plant diversity - an approach molded through experience and a genius for comprehending and organizing the breadth of creation.
And it was categorization that Linnaeus was all about. Today's significant holdover from Linnaeus's work is his consolidation of the binomial system of nomenclature. Linnaeus systematically brought every available plant into compliance with his way of naming and categorizing. The simplicity and thoroughness with which Linnaeus applied his way of naming plants proved of immediate and international value, sweeping away the awkward and forgetable. Today, through international agreement, we base the Code of Botanical Nomenclature on his 1753 Species Plantarum.
But for Linnaeus's contemporaries, most of whom idolized him, the immediate value of his publications was the way he organized plants. Linnaeus created a straight-forward method of grouping plants, a system that was easily memorized and utilized. For the first time in plant studies, anyone could study a new plant and know where to file it away - that is, how to classify the plant.
As a young man, Linnaeus had fallen as a thrall of sex, or more accurately, he was among the first generation of botanists who came to study plants with the awareness that seed are the fallout of sexual reproduction. Only a few years before his birth had it been made clear that pollen is the male generative force, analagous to human sperm. Linnaeaus took that fresh concept and ran with it. It was obvious to him that reproduction was crucial to preservation of every species, and the salient characteristics of reproductive organs should be directly correlated with the definition or nature of each different species. The result was his sexual system of classifying plants. Plant genera (and therefore the included species) could be grouped into Classes based on numbers and character of stamens, and within the Classes, into Orders based on the numbers and characteristics of pistils or further information on stamens.
The popularity of the sexual system of classifying plants was short-lived however. Within just a few years of Linnaeus's death, botanists published systems that grouped genera into families that seemed more "natural" - families that reflected the natural affinities of different groups of plants - affinities that would be considered ancestral and evolutionary a century later. So we are left with the binomial system of nomenclature as the residual legacy of Linnaeus's work.
But not so fast. In celebration of Linnaeus's 300th birthday two years ago, I decided it would be fun to attempt organizing a few salons that replicated the experience people would have had with Linnaeus's methods. I pulled out his simple system, assembled groups of people, and worked with the students through many plant samples. What a revelation. Of course there was no way we discovered that Linnaeus's sexual system has anything to say about how plants should be grouped or classified. What we did learn was how quickly his system cut through the mystery of a new plant. No wonder Linnaeus loved his method. He studied thousands of different kinds of plants; the sexual system represents the life-experience of one of the most brilliant field-botanists who ever lived. In using the sexual system to guide our study of many different plants at a single setting, we stepped right into Linnaeus's times and challenges. His system worked, quickly and intelligibly. It proved to be a great teaching method, bringing novices quickly into an appreciation of plant structure and diversity. Working through flowers from Linnaeus's perspective is wonderfully enlightening, engaging, and worthwhile.
But that doesn't mean there are publishable results. The system has serious limits. It gets you to a place in a list or chart, but it doesn't reckon on today's reality - the sheer number of different kinds of plants we have come to understand there are and have been on Earth. Linnaeus's system suggests a matrix of potential structural combinations, which would mean our discovery of plants would have yielded less than 50,000 kinds. He thought all the world's plants would be known in short order. That did not happen, and with over 250,000 accepted species, we continue to add new kinds. And, honestly, there is nothing that Linnaeus's system brings to the table in a contemporary understanding of plant affinities or evolution.
But for students who want to learn more plants, and more about plants, Linnaeus's methods have much to offer. Following his system gives the student of plants access to Linnaeus's approach to making sense of the great range of plant diversity - an approach molded through experience and a genius for comprehending and organizing the breadth of creation.
Wednesday, May 13, 2009
She Loves Me, She Loves Me Not
The season is full of Daisies - which botanists call Composites. And these "flowers" are indeed composed..., each daisy is a head of flowers (a particular kind of inflorescence) made up and masquerading as a single flower. When you pull out, petal by petal, the parts of a daisy as you alternate between being loved or not, you are not simply pulling single petals from a flower. You are tugging individual flowers (little flowers called florets) from a cluster that looks, for all the world, like a single flower.
If you break a daisy flower apart, the florets will stand out more clearly. In many cases, when the heads are classically daisy-like, you will actually discover the head is made of two kinds of flowers. Each of the prognosticating petals that wants to be pulled out comes from a single flower - which we call a ray, because it radiates from the head. There are other even more minute flowers that fill the center of the head, which we call the disk florets. These florets are more symmetrical, each one showing five little angular lobes that represent individual petals that make up the corolla. If you turn your attention back to the rays, you may see little teeth at the tip of a petals, teeth that reflect the same lobes seen in the disk flowers.
The base of each floret is the part that becomes the fruit, so it is the ovary. Since it develops below where the other flower parts emerge, we say this is an "inferior" ovary. All daisies have inferior ovaries. Each one matures into a dry, hard one-seeded fruit, which botanists call a nutlet. So what nutlets do you know. Well you certainly know the Sunflower seed - each one develops inside the inferior fruit of a Sunflower floret. So a Sunflower is, pretty demonstrably, a daisy.
But there are thousands of different kinds of daisies, different kinds of composites. Dahlias, Zinnias, Chrysanthemums, Marigolds, Calendulas, Liatris, Edelweiss, Achillea, and even Lettuce and Artichokes - these are all composites. Most are pretty normal, at least for a daisy, and have both ray and disk flowers. But whole groups of daisies produce heads of florets that are fully of the disk type, and there are other groups that produce heads made only of ray florets. There are even a few, really odd composites, in which the head has a single floret. With the shrubby Coyote Bush (Baccharis), whole plants produce flowers that are either female (no stamens) or male (no pistils.) In these, the heads of flowers on one shrub look entirely different from those on another; the males look very different from the females. So these simple possibilites introduce quite a range of possibilities in biology and appearance.
At times we have seen political movements that propose we make the Sunflower the national flower. I remember a Senator Dirkson who loved Marigolds, and wanted to make the Marigold the US National Flower. If that ever happened, we'd have to call it the National Inflorescence.
If you break a daisy flower apart, the florets will stand out more clearly. In many cases, when the heads are classically daisy-like, you will actually discover the head is made of two kinds of flowers. Each of the prognosticating petals that wants to be pulled out comes from a single flower - which we call a ray, because it radiates from the head. There are other even more minute flowers that fill the center of the head, which we call the disk florets. These florets are more symmetrical, each one showing five little angular lobes that represent individual petals that make up the corolla. If you turn your attention back to the rays, you may see little teeth at the tip of a petals, teeth that reflect the same lobes seen in the disk flowers.
The base of each floret is the part that becomes the fruit, so it is the ovary. Since it develops below where the other flower parts emerge, we say this is an "inferior" ovary. All daisies have inferior ovaries. Each one matures into a dry, hard one-seeded fruit, which botanists call a nutlet. So what nutlets do you know. Well you certainly know the Sunflower seed - each one develops inside the inferior fruit of a Sunflower floret. So a Sunflower is, pretty demonstrably, a daisy.
But there are thousands of different kinds of daisies, different kinds of composites. Dahlias, Zinnias, Chrysanthemums, Marigolds, Calendulas, Liatris, Edelweiss, Achillea, and even Lettuce and Artichokes - these are all composites. Most are pretty normal, at least for a daisy, and have both ray and disk flowers. But whole groups of daisies produce heads of florets that are fully of the disk type, and there are other groups that produce heads made only of ray florets. There are even a few, really odd composites, in which the head has a single floret. With the shrubby Coyote Bush (Baccharis), whole plants produce flowers that are either female (no stamens) or male (no pistils.) In these, the heads of flowers on one shrub look entirely different from those on another; the males look very different from the females. So these simple possibilites introduce quite a range of possibilities in biology and appearance.
At times we have seen political movements that propose we make the Sunflower the national flower. I remember a Senator Dirkson who loved Marigolds, and wanted to make the Marigold the US National Flower. If that ever happened, we'd have to call it the National Inflorescence.
Friday, March 20, 2009
Moth Orchids
I believe most people simply call them Phalaenopsis, which is the scientific name of the Moth Orchids, a genus from tropical Asia in which all of the species have lateral petals resembling the wings of a moth. Indeed, the Latinized word Phalaenopsis means "looks like a moth."
When I was a kid, these were pretty exotic plants. But today they approach being common. People have discovered that a nice Phalaenopsis is a practical and elegant way to keep fresh flowers. The plant and flowering stalk are as fine a combination as any floral arrangement, flowers and buds are perfection, and the longevity beats any flower arrangement hands-down. A nice Phalaenopsis, purchased for $15-40 at markets and nurseries around the country, can remain in bloom for weeks..., weeks! Beyond being a more sustainable way to enjoy fresh flowers, the plant becomes a new form of chia pet - a fun project for people to pursue - an attempt to keep the plant alive and even reap a new harvest of flowers.
And the return of flowering is a real possibility. Just keeping a plant in a reasonably good living state is occasionally rewarded by growth of a new flowering branch out from a stem from which every flower has long-since fallen. So afficionados have learned to leave green, healthy flowering stems on the plant until it is clear not much more will happen. Success comes when the plant continues to send out new flowering stems from the base of the stem.
The trick, however, is that people who aren't familiar with orchids are seldom clued into an aphorism of the orchidist - happy roots, happy plant. Those nifty plants, sold at what seem to be impossibly low prices, usually have a built-in problem. They are potted in a way that promotes good "finishing-off" growth and makes the plant practically bullet-proof during the first few weeks of flowering. But the underlying problem is that the medium (the stuff packed around the roots) is seldom a good medium to promote new growth.
To stand a chance at keeping the Phalaenopsis living healthily enough to rebloom, there is work to be done. As soon as it gets to the end of good flowering, someone needs to remove it from the pot. What you will discover is remarkable. Most Phalies sold in the cut-flower trade are potted tightly in sphagnum moss - the kind called New Zealand sphagnum. The sphagnum used is fresh; the leafy scales have an astounding capacity to hold water, and the sphagnum doesn't quickly break down into humus. In fact, many orchid growers use this sphagnum - but they use it in open baskets and pots that give ample drainage and allow air to circulate around roots. But no orchidist packs the sphagnum and roots so tightly into pots as you will see for these flowering plants. They are treated, in reality, like whole-plant cut flowers, not intended at all for long-term survival.
The sphagnum, though perfectly suited for wrapping the roots, is pretty expensive, and can actually hold too much water in the center of the pot. Imagine a light-weight, cheap, non-absorbent, and non-degrading substitute a producer could use to stuff in the core of potting material, and you may guess in advance that growers frequently pack styrofoam packing peanuts into the space at the center of the rootball.
It drives me crazy. Here you are, breaking apart the rootball of a spent Phalie, expecting to compost the refuse, and out fall several white styrofoam packing peanuts. Though practical, there is just something offensive about the whole situation - growers wrapping orchid roots in a blanket of sphagnum and cramming them into a tight plastic pot-like bag with a heart of styrofoam. Weird.
So how do you pot these used plants? How do you bring them back? This is what I have been working on for the past week, testing some ideas, talking to collectors and growers, cleaning and repotting. Here is what I learn from others. Phalies need annual repotting; even if they were in good growing medium from the start, a successful grower would likely have repotted the plant after flowering anyway.
We are moving back to terracotta pots, a special kind perforated with holes to allow for drainage and air movement. We are using medium bark, and selecting pots that seem slightly undersized. If we have to use larger pots (7-8 inches), we are installing a small inverted pot or a red brick under the plant, to eliminate the core of medium that seems to break down into organic mush the quickest. Orchids that are natively epiphytes (growing on the trunks of trees, with their roots totally exposed) do not like rotting bark. Roots found in rotten bark are seldom healthy.
You know when an orchid root is healthy because it has an active growth tip, and is intact and fleshy, covered with the white, barkish velamen. And as we said earlier, happy roots, happy plants. When the roots of a Phalaenopsis are not healthy, the damage soon shows in withering foliage, browning basal leaves, and general reduced size.
There is a lot more that can be said of these wonderful plants. White-flowered forms are wonderful, but the colors and color patterns that continue to appear in the trade are spectacular. The numbers of plants imported (to be brought into flower) increases each year. But the market seems far from saturation, and to the dedicated student of orchids, this trend opens wholly new territory that might bring in new converts.
When I was a kid, these were pretty exotic plants. But today they approach being common. People have discovered that a nice Phalaenopsis is a practical and elegant way to keep fresh flowers. The plant and flowering stalk are as fine a combination as any floral arrangement, flowers and buds are perfection, and the longevity beats any flower arrangement hands-down. A nice Phalaenopsis, purchased for $15-40 at markets and nurseries around the country, can remain in bloom for weeks..., weeks! Beyond being a more sustainable way to enjoy fresh flowers, the plant becomes a new form of chia pet - a fun project for people to pursue - an attempt to keep the plant alive and even reap a new harvest of flowers.
And the return of flowering is a real possibility. Just keeping a plant in a reasonably good living state is occasionally rewarded by growth of a new flowering branch out from a stem from which every flower has long-since fallen. So afficionados have learned to leave green, healthy flowering stems on the plant until it is clear not much more will happen. Success comes when the plant continues to send out new flowering stems from the base of the stem.
The trick, however, is that people who aren't familiar with orchids are seldom clued into an aphorism of the orchidist - happy roots, happy plant. Those nifty plants, sold at what seem to be impossibly low prices, usually have a built-in problem. They are potted in a way that promotes good "finishing-off" growth and makes the plant practically bullet-proof during the first few weeks of flowering. But the underlying problem is that the medium (the stuff packed around the roots) is seldom a good medium to promote new growth.
To stand a chance at keeping the Phalaenopsis living healthily enough to rebloom, there is work to be done. As soon as it gets to the end of good flowering, someone needs to remove it from the pot. What you will discover is remarkable. Most Phalies sold in the cut-flower trade are potted tightly in sphagnum moss - the kind called New Zealand sphagnum. The sphagnum used is fresh; the leafy scales have an astounding capacity to hold water, and the sphagnum doesn't quickly break down into humus. In fact, many orchid growers use this sphagnum - but they use it in open baskets and pots that give ample drainage and allow air to circulate around roots. But no orchidist packs the sphagnum and roots so tightly into pots as you will see for these flowering plants. They are treated, in reality, like whole-plant cut flowers, not intended at all for long-term survival.
The sphagnum, though perfectly suited for wrapping the roots, is pretty expensive, and can actually hold too much water in the center of the pot. Imagine a light-weight, cheap, non-absorbent, and non-degrading substitute a producer could use to stuff in the core of potting material, and you may guess in advance that growers frequently pack styrofoam packing peanuts into the space at the center of the rootball.
It drives me crazy. Here you are, breaking apart the rootball of a spent Phalie, expecting to compost the refuse, and out fall several white styrofoam packing peanuts. Though practical, there is just something offensive about the whole situation - growers wrapping orchid roots in a blanket of sphagnum and cramming them into a tight plastic pot-like bag with a heart of styrofoam. Weird.
So how do you pot these used plants? How do you bring them back? This is what I have been working on for the past week, testing some ideas, talking to collectors and growers, cleaning and repotting. Here is what I learn from others. Phalies need annual repotting; even if they were in good growing medium from the start, a successful grower would likely have repotted the plant after flowering anyway.
We are moving back to terracotta pots, a special kind perforated with holes to allow for drainage and air movement. We are using medium bark, and selecting pots that seem slightly undersized. If we have to use larger pots (7-8 inches), we are installing a small inverted pot or a red brick under the plant, to eliminate the core of medium that seems to break down into organic mush the quickest. Orchids that are natively epiphytes (growing on the trunks of trees, with their roots totally exposed) do not like rotting bark. Roots found in rotten bark are seldom healthy.
You know when an orchid root is healthy because it has an active growth tip, and is intact and fleshy, covered with the white, barkish velamen. And as we said earlier, happy roots, happy plants. When the roots of a Phalaenopsis are not healthy, the damage soon shows in withering foliage, browning basal leaves, and general reduced size.
There is a lot more that can be said of these wonderful plants. White-flowered forms are wonderful, but the colors and color patterns that continue to appear in the trade are spectacular. The numbers of plants imported (to be brought into flower) increases each year. But the market seems far from saturation, and to the dedicated student of orchids, this trend opens wholly new territory that might bring in new converts.
Monday, March 16, 2009
Soaring Seed
Just beside our garage is an arbor covered with Wisteria, specifically the cultivar 'Cooke's Purple' - a vigorous vine that can make a canopy dense with pendent inflorescences of blue-purple pea flowers. The vine is coming into bloom right now, and we are promised a glorious sight. By the time flowering is completed, the light green leaves will just have begun to expand, and in short order the vine will create a good shade.
When in full flower, Wisteria resonates with the buzzing sounds of bees, hovering and clambering from flower to flower. This activity results in some pollinations that yield fruit, which grow to become velvety green, lumpy and woody beans. By autumn, when the leaves have fallen, the beans are brown and dry - and hard.
A few autumns back I was clearing the garden area around the Wisteria arbor, which is also a potting bench. To wash the dust off all of the surfaces, I hosed down the structure, vine and all. Within a few minutes of the drenching, while cleaning around the garage entrance, I heard a crack/pop, and the tap of a landing, then another, then several - like a handful of popcorn reaching its modest crescendo in a pan. But the lid was off and seed were flying in all directions..., beautiful, flattened, shiny, and speckled brown. They pelted tools and shelving in the garage, flew into potted plants, and landed in soil and lawn - as far as 15-20 feet from the the scores of fruit that were curling and snapping open once soaked with water. It was a stunning performance, and something I had not expected at all.
So no surprise when, while cleaning around the arbor this winter, I discovered seed all around - in pots and soil. And a lot of them had successfully sprouted; little Wisteria plants showing up all around. I steadily weed them out, knowing there will be more, for it is March again, and the mother plant is back in bloom. I will soon smell their pea blossoms, wondering if my lingering perception that they smell like grape jelly will be confirmed by reality, or will prove to be an altered memory, inspired by the faint resemblance of the flower cluster to clusters of grapes. And if I have a moment, before the rains that come around Thanksgiving, I will hose down the arbor, just for the fun of it.
When in full flower, Wisteria resonates with the buzzing sounds of bees, hovering and clambering from flower to flower. This activity results in some pollinations that yield fruit, which grow to become velvety green, lumpy and woody beans. By autumn, when the leaves have fallen, the beans are brown and dry - and hard.
A few autumns back I was clearing the garden area around the Wisteria arbor, which is also a potting bench. To wash the dust off all of the surfaces, I hosed down the structure, vine and all. Within a few minutes of the drenching, while cleaning around the garage entrance, I heard a crack/pop, and the tap of a landing, then another, then several - like a handful of popcorn reaching its modest crescendo in a pan. But the lid was off and seed were flying in all directions..., beautiful, flattened, shiny, and speckled brown. They pelted tools and shelving in the garage, flew into potted plants, and landed in soil and lawn - as far as 15-20 feet from the the scores of fruit that were curling and snapping open once soaked with water. It was a stunning performance, and something I had not expected at all.
So no surprise when, while cleaning around the arbor this winter, I discovered seed all around - in pots and soil. And a lot of them had successfully sprouted; little Wisteria plants showing up all around. I steadily weed them out, knowing there will be more, for it is March again, and the mother plant is back in bloom. I will soon smell their pea blossoms, wondering if my lingering perception that they smell like grape jelly will be confirmed by reality, or will prove to be an altered memory, inspired by the faint resemblance of the flower cluster to clusters of grapes. And if I have a moment, before the rains that come around Thanksgiving, I will hose down the arbor, just for the fun of it.
Wednesday, March 4, 2009
A Change in the Sources and Forces of Change
My basic understanding of plant evolution has come from courses and books that spoke to the sources of variability in a population, and the forces that impact the survival of certain individuals over others, survival that played out in the production of offspring that would come to define the next generation. Sources relate how new genetic possibilities arise. Mutation is best-known by the public. This happens when wholly new “genes” (really, they are different options, alleles) appear in the genetic material of a population; if a mutation impacts a place where sex cells are made (a pollen sac or an ovule)then new genetic possibilities may become available for future generations. But there are other ways a population can get fresh genetic options, such as through successful sexual encounters with other populations that result in hybrid progeny. We also know that genetic material can be transferred from one plant to another through bacterial and viral activity. Over time, a lot of new options have given rise to new forms in plants.
I can’t recount all the different forces that are normally discussed, pressures on plants from variability in soils and changes in climate, the activity of pollinators and herbivores (which many people, today, call predators.) Pressures mean that certain plants will have greater success in producing viable offspring than others.
Every plant you encounter today has its own complex natural history, and its own, reticulated story of change through eons and countless generations. Most significantly, every living plant today is the current link in an ongoing chain of life that has never been interrupted, not for the billions of years since the first living ancestor(s) of that very plant came into cellular existence. Plant life is not spontaneous; it is serial – life begets life – cells are formed only from nuclei and cytoplasm that “know” how to make cells. Somehow the wondrous differing forms and biologies we call species, each begetting their own kind, reach back through the struggle for survival to common ancestors.
Looking back on what I understood about evolution, I seem to have missed books and teachers giving much attention to the force of disease. We talked about threats to individuals and populations, and I’m certain we mentioned disease, but it seemed casual. And I know that in the last few decades scientists have discussed more about evolution of disease resistance through production of secondary compounds, such as flavonoids. But to my mind, the role of disease in plant evolution is understated.
Plant disease is a big deal. In the last century, disease has proven to be the most immediate source of devastation to plant populations around the world. When E. Lucy Braun studied the Eastern mixed mesophytic forest, she defined the zone based on eight dominant trees. Major populations of two of those dominants, American Chestnut and American Elm, were wiped out in short order through 20th century introduction of diseases from Europe, diseases that had previously been endemic to European relatives. Today, American Beech is threatened by introduction of yet another disease.
Books have appeared in the last two years that portend extinction of cultivated bananas, due to fungal disease that is readily spread. The world’s citrus crop appears in eminent danger of collapse due to spread of what is called greening disease. A native disease of Hevea brasiliensis, the Rubber Tree, doomed commercial production of rubber in Manaus.
None of these diseases is newly evolved. Their potency is no more than ever, it was their dispersal that had held disaster at bay. Human activity, spreading disease and vectors, establishing monocultures that incubate inoculum, is the wind behind the sails of infection. Surely, each disease would made its way further afield without human activity, but not so quickly as today, not so quickly as to defy the steady counter-force of evolutionary selection for resistance.
Seeing how quickly a new disease can annihilate a population reminds us that disease has been a significant player over history. Certainly, disease has not been the force that drove flower shape, or dispersal success, but it has certainly penalized naively successful lineages that came in contact with resistant disease-bearing groups And diseases evolve also, in most cases even more quickly than do plants. So there has been no shortage of the impact of disease on evolution of plant populations.
Interestingly, the ancient formula seems upended. Because humans basically have taken over management of the planet, we have altered, in some cases, neutralized the normal forces of evolution; the historical evolutionary process is dysfunctional. However, the role of disease in plant survival, thus plant evolution, becomes greatly magnified through human activity. Disease has become the great tyrant of modern plant populations. And the Genie has escaped the bottle; there is no going back.
From an agricultural and horticultural perspective, evolution and spread of disease and pestilence appear to threaten all plant life on earth. At the very time humans have elevated the spread and impact of disease, we have also come to fear technology that will prove necessary to conserve plant diversity – especially the diversity of food crops. Genetic modification of plants will, in the end, prove crucial to the survival of some of our most important and wonderful plants. One wonders how society will negotiate the concerns and politics of genetic technology, but the disease-driven trend of plant diversity is creeping extinction.
I can’t recount all the different forces that are normally discussed, pressures on plants from variability in soils and changes in climate, the activity of pollinators and herbivores (which many people, today, call predators.) Pressures mean that certain plants will have greater success in producing viable offspring than others.
Every plant you encounter today has its own complex natural history, and its own, reticulated story of change through eons and countless generations. Most significantly, every living plant today is the current link in an ongoing chain of life that has never been interrupted, not for the billions of years since the first living ancestor(s) of that very plant came into cellular existence. Plant life is not spontaneous; it is serial – life begets life – cells are formed only from nuclei and cytoplasm that “know” how to make cells. Somehow the wondrous differing forms and biologies we call species, each begetting their own kind, reach back through the struggle for survival to common ancestors.
Looking back on what I understood about evolution, I seem to have missed books and teachers giving much attention to the force of disease. We talked about threats to individuals and populations, and I’m certain we mentioned disease, but it seemed casual. And I know that in the last few decades scientists have discussed more about evolution of disease resistance through production of secondary compounds, such as flavonoids. But to my mind, the role of disease in plant evolution is understated.
Plant disease is a big deal. In the last century, disease has proven to be the most immediate source of devastation to plant populations around the world. When E. Lucy Braun studied the Eastern mixed mesophytic forest, she defined the zone based on eight dominant trees. Major populations of two of those dominants, American Chestnut and American Elm, were wiped out in short order through 20th century introduction of diseases from Europe, diseases that had previously been endemic to European relatives. Today, American Beech is threatened by introduction of yet another disease.
Books have appeared in the last two years that portend extinction of cultivated bananas, due to fungal disease that is readily spread. The world’s citrus crop appears in eminent danger of collapse due to spread of what is called greening disease. A native disease of Hevea brasiliensis, the Rubber Tree, doomed commercial production of rubber in Manaus.
None of these diseases is newly evolved. Their potency is no more than ever, it was their dispersal that had held disaster at bay. Human activity, spreading disease and vectors, establishing monocultures that incubate inoculum, is the wind behind the sails of infection. Surely, each disease would made its way further afield without human activity, but not so quickly as today, not so quickly as to defy the steady counter-force of evolutionary selection for resistance.
Seeing how quickly a new disease can annihilate a population reminds us that disease has been a significant player over history. Certainly, disease has not been the force that drove flower shape, or dispersal success, but it has certainly penalized naively successful lineages that came in contact with resistant disease-bearing groups And diseases evolve also, in most cases even more quickly than do plants. So there has been no shortage of the impact of disease on evolution of plant populations.
Interestingly, the ancient formula seems upended. Because humans basically have taken over management of the planet, we have altered, in some cases, neutralized the normal forces of evolution; the historical evolutionary process is dysfunctional. However, the role of disease in plant survival, thus plant evolution, becomes greatly magnified through human activity. Disease has become the great tyrant of modern plant populations. And the Genie has escaped the bottle; there is no going back.
From an agricultural and horticultural perspective, evolution and spread of disease and pestilence appear to threaten all plant life on earth. At the very time humans have elevated the spread and impact of disease, we have also come to fear technology that will prove necessary to conserve plant diversity – especially the diversity of food crops. Genetic modification of plants will, in the end, prove crucial to the survival of some of our most important and wonderful plants. One wonders how society will negotiate the concerns and politics of genetic technology, but the disease-driven trend of plant diversity is creeping extinction.
Thursday, February 19, 2009
Noses and Navels, Part 2: Navels
When I was a kid, boys ran around without shirts, all summer. We knew that there are kinds of navels - innies and outies. And so it is with roses and their relatives - the plums, peaches, cherries, apples, pears, loquats, etc. In this group, there are fruit types that are innies, and fruit types that are outies. For simplicity, I just refer to the whole bunch of these plants as roses.
Rose flowers, like all flowers, comprise a predictable array of flower parts (sepals, petals, stamens, and/or pistils) at the end of a special stem, a stem we call a peduncle. In the rose family, this arrangement usually has five sepals - which are often green and leafy, and fold back once the flower opens. The standard number of petals for roses is five also, and they are quintessentially normal - often white, pink, or red - though there are a lot of naturally-occuring roses with petals in the yellow and oranges, even in other colors. They are attached to this stem, this peduncle.
For many plants, the peduncle remains a simple stem tip, but in roses the peduncle (the flower stem) does neat things. It often forms a small shallow bowl, called a floral cup, in which case the sepals and petals are attached around the rim, with the sepals outside the petals. The peduncle can form more of a turban also, with parts mounded up, rather than sunken. As you might guess, flowers that form floral cups are going to become innies, and those with the mounds will develop into outies.
Most rose flowers are complete, having all of the four kinds of flower parts. Though the base situation is five sepals and five petals, stamens are often numerous, and pistils (ovaries) range from one to many. The stamens and pistils can all be crammed down in the floral cup, or will be raised on a mound, depending on the genus.
When the flower develops into a fruit, the stem often becomes exaggerated. For garden variety rose, plants in the genus Rosa, the flower forms a floral cup, which wraps loosely around the pistils and stamens. With fruiting the cup turns into the rose hip, with its crown of triangular, leafy sepals and its mop of dead stamens and developing pistils poking out the end. In the world of navels, this is an innie.
What if the floral cup were more absolute in its ability to grow around the pistils, if even in flower the cup more tightly surrounded the pistils? Then when the fruit develops, the stem becomes really fleshy and takes on an absolute shape. You could then have an apple or a pear - that is how they develop. So the flesh of an apple, and that of a pear, are basically stem tissue, and in their true complexity bear layers of tissue that come from the bases of sepals and petals also. These would be super-innies.
If the stem forms exactly in the opposite way, making a dome rather than a cup, you find the pistils sitting on top of a bulging stem tip, rather than sunken. This is a pretty normal arrangement in many other flower groups, the magnolias and the anemones, for example. In the roses, you find such an arrangement in many genera, but it is mostly grandly expressed in the strawberry. Check out a strawberry flower (genus Fragaria) with a handlens, and you will see tiny little pistils making a beaded spiral in a central mound. Even though there are numerous separate pistils, this is still a single flower. As the fruit develop (each of the little pistils becomes a separate fruit), the stem also inflates to a beautiful, red, fleshy strawberry - with its little hard, mature one-seeded fruit arranged like tiny jewels. This is a real outie.
But it doesn't end there. In some roses, each pistil develops a fleshy covering (its own fleshy fruit), every one standing out as a separate fleshy bead. In Rubus, the blackberries (and raspberries,and dewberries, and ollalieberries,) there are several pistils on the flower stem. When blackberries mature, the stem is normal, but each pistil is fleshy. So a blackberry is an outie also - a set of lovely fleshy fruit formed on the stem of a single flower.
And what if it is all just much simpler? If there is no floral cup, and if the stem is kinda normal, and if there is only one pistil, which turns into a fruit without any added stem. And because roses only produce one seed in each pistil, the fruit is one-seeded. Then you have the genus Prunus, which includes the peaches, plums, apricots, cherries, and almonds. Each of these is less-messy affair, developing from a flower that had only one pistil, with its sepals at the base rather than at the tip.
So the roses are really funny. With incredibly minor changes in what is fleshy and what is not, in what enlarges and what stays small, the same basic floral arrangement yields fruit so very different as rose hips, apples, strawberries, blackberries, and peaches. Some are innies, some are outies, and some don't even have navels. Perhaps, then, it is too simplistic to think that a rose, is a rose, is a rose.
Rose flowers, like all flowers, comprise a predictable array of flower parts (sepals, petals, stamens, and/or pistils) at the end of a special stem, a stem we call a peduncle. In the rose family, this arrangement usually has five sepals - which are often green and leafy, and fold back once the flower opens. The standard number of petals for roses is five also, and they are quintessentially normal - often white, pink, or red - though there are a lot of naturally-occuring roses with petals in the yellow and oranges, even in other colors. They are attached to this stem, this peduncle.
For many plants, the peduncle remains a simple stem tip, but in roses the peduncle (the flower stem) does neat things. It often forms a small shallow bowl, called a floral cup, in which case the sepals and petals are attached around the rim, with the sepals outside the petals. The peduncle can form more of a turban also, with parts mounded up, rather than sunken. As you might guess, flowers that form floral cups are going to become innies, and those with the mounds will develop into outies.
Most rose flowers are complete, having all of the four kinds of flower parts. Though the base situation is five sepals and five petals, stamens are often numerous, and pistils (ovaries) range from one to many. The stamens and pistils can all be crammed down in the floral cup, or will be raised on a mound, depending on the genus.
When the flower develops into a fruit, the stem often becomes exaggerated. For garden variety rose, plants in the genus Rosa, the flower forms a floral cup, which wraps loosely around the pistils and stamens. With fruiting the cup turns into the rose hip, with its crown of triangular, leafy sepals and its mop of dead stamens and developing pistils poking out the end. In the world of navels, this is an innie.
What if the floral cup were more absolute in its ability to grow around the pistils, if even in flower the cup more tightly surrounded the pistils? Then when the fruit develops, the stem becomes really fleshy and takes on an absolute shape. You could then have an apple or a pear - that is how they develop. So the flesh of an apple, and that of a pear, are basically stem tissue, and in their true complexity bear layers of tissue that come from the bases of sepals and petals also. These would be super-innies.
If the stem forms exactly in the opposite way, making a dome rather than a cup, you find the pistils sitting on top of a bulging stem tip, rather than sunken. This is a pretty normal arrangement in many other flower groups, the magnolias and the anemones, for example. In the roses, you find such an arrangement in many genera, but it is mostly grandly expressed in the strawberry. Check out a strawberry flower (genus Fragaria) with a handlens, and you will see tiny little pistils making a beaded spiral in a central mound. Even though there are numerous separate pistils, this is still a single flower. As the fruit develop (each of the little pistils becomes a separate fruit), the stem also inflates to a beautiful, red, fleshy strawberry - with its little hard, mature one-seeded fruit arranged like tiny jewels. This is a real outie.
But it doesn't end there. In some roses, each pistil develops a fleshy covering (its own fleshy fruit), every one standing out as a separate fleshy bead. In Rubus, the blackberries (and raspberries,and dewberries, and ollalieberries,) there are several pistils on the flower stem. When blackberries mature, the stem is normal, but each pistil is fleshy. So a blackberry is an outie also - a set of lovely fleshy fruit formed on the stem of a single flower.
And what if it is all just much simpler? If there is no floral cup, and if the stem is kinda normal, and if there is only one pistil, which turns into a fruit without any added stem. And because roses only produce one seed in each pistil, the fruit is one-seeded. Then you have the genus Prunus, which includes the peaches, plums, apricots, cherries, and almonds. Each of these is less-messy affair, developing from a flower that had only one pistil, with its sepals at the base rather than at the tip.
So the roses are really funny. With incredibly minor changes in what is fleshy and what is not, in what enlarges and what stays small, the same basic floral arrangement yields fruit so very different as rose hips, apples, strawberries, blackberries, and peaches. Some are innies, some are outies, and some don't even have navels. Perhaps, then, it is too simplistic to think that a rose, is a rose, is a rose.
Saturday, February 14, 2009
Noses and Navels - Part 1: Noses
Orchids have noses and Roses have navels (which I will explain in another posting). At least those are a couple of thoughts I fall back on when attempting to explain flower and fruit structure to a group. Examine an archetypal orchid - such as Cattleya. There are only seven parts of the flower - three of the petal-like objects are the sepals. We know they are sepals because they are the group of three "floral leaves" that originate at the same point, below and outside the petals - even alternating with the petals in exact attachment. The sepals are the flower parts that made up the outside of the developing buds.
Once the flower opens (botanists call the opening process anthesis,) the inner surface of the three sepals have the look and texture of petals. Face to face with an open Cattleya, you see that the three sepals make a triangle, with one pointing up (once you determine what "up" is,) and the other two pointing to the corners of the triangle base.
Alternating with the narrow sepals are three petals, but only the upper two look like normal petals. These are called laterals; in Cattleya they are broader and more colorful than the sepals. The tips of the lateral petals make the two upper corners of an upside-down triangle. The apex of the triangle is at the bottom, made by the third petal, which is the showiest and most characteristic petal of the Cattleya. That petal, the labellum (or lip,) is the landing platform for visiting insects in naturally occuring Cattleyas; its beauty and complexity is all about attracting and positioning visiting insects and has nothing to do with amusing humans.
Though the lip is the most conspicuous single element in the Cattleya flower, the business end is the remaining seventh flower part - a white, plastic-seeming part that looks like a nose to me. I know it is not a nose; orchids can't have noses. It is the column - the sleek device that combines all of the reproductive structures, the male and female parts we expect to find in a flower. If you examine the column closely, it has a lot of elegant structure. It arches forward, pairing off with the lip in a predictable and precise form - the two structures working together to create the mechanism by which orchid flowers are pollinated.
At the tip of the column, there is a hatch, underneath which you will find the pollen masses. The hatch and pollen together are considered to constitute all you can easily distinguish as the flower's single anther. Immediately back/behind/below the anther, the column has a long sticky chamber - on its underside, facing the base of the lip. This is the stigmatic chamber - the surface is the stigma that must receive pollen for an orchid flower to be pollinated. In most other kinds of flowers, the stigma sits proudly on its own stalk (the style) - easily visible in the center. Many flowers have separate stigmas, each on their own style as part of their own separate pistil; others have a single stigma that may have obvious lobes corresponding to separate chambers in the ovary.
By comparison to most non-orchid flowers, the Cattleya is remarkably engineered - simplified and modern in form based on a history of multiple and complex parts. But the column is what orchids have that is all about pollination, thus leading to fertilization and sexual reproduction. So you might say that Orchids have a nose for sex.
As a side note, from childhood, I remember the big deal about orchids in corsages was often simply deciding how to wear them.... what is right side up and what is upside down. When in flower, the lip of the Cattleya is down, below the column, the natural position that relates to how the flower is visited by pollinators. Curiously, to achieve this position, an orchid has to grow in a way to reposition the lip - which in its early formation is positioned on top. We call this resupination - setting the lip in a supine, or laying down, position. In the Cattleyas it happens through a twisting in the stalk (which is yet another curiosity, because it is the ovary.) Which leads to a corny ending; through a twist of fate, orchids keep their noses up in the air.
Once the flower opens (botanists call the opening process anthesis,) the inner surface of the three sepals have the look and texture of petals. Face to face with an open Cattleya, you see that the three sepals make a triangle, with one pointing up (once you determine what "up" is,) and the other two pointing to the corners of the triangle base.
Alternating with the narrow sepals are three petals, but only the upper two look like normal petals. These are called laterals; in Cattleya they are broader and more colorful than the sepals. The tips of the lateral petals make the two upper corners of an upside-down triangle. The apex of the triangle is at the bottom, made by the third petal, which is the showiest and most characteristic petal of the Cattleya. That petal, the labellum (or lip,) is the landing platform for visiting insects in naturally occuring Cattleyas; its beauty and complexity is all about attracting and positioning visiting insects and has nothing to do with amusing humans.
Though the lip is the most conspicuous single element in the Cattleya flower, the business end is the remaining seventh flower part - a white, plastic-seeming part that looks like a nose to me. I know it is not a nose; orchids can't have noses. It is the column - the sleek device that combines all of the reproductive structures, the male and female parts we expect to find in a flower. If you examine the column closely, it has a lot of elegant structure. It arches forward, pairing off with the lip in a predictable and precise form - the two structures working together to create the mechanism by which orchid flowers are pollinated.
At the tip of the column, there is a hatch, underneath which you will find the pollen masses. The hatch and pollen together are considered to constitute all you can easily distinguish as the flower's single anther. Immediately back/behind/below the anther, the column has a long sticky chamber - on its underside, facing the base of the lip. This is the stigmatic chamber - the surface is the stigma that must receive pollen for an orchid flower to be pollinated. In most other kinds of flowers, the stigma sits proudly on its own stalk (the style) - easily visible in the center. Many flowers have separate stigmas, each on their own style as part of their own separate pistil; others have a single stigma that may have obvious lobes corresponding to separate chambers in the ovary.
By comparison to most non-orchid flowers, the Cattleya is remarkably engineered - simplified and modern in form based on a history of multiple and complex parts. But the column is what orchids have that is all about pollination, thus leading to fertilization and sexual reproduction. So you might say that Orchids have a nose for sex.
As a side note, from childhood, I remember the big deal about orchids in corsages was often simply deciding how to wear them.... what is right side up and what is upside down. When in flower, the lip of the Cattleya is down, below the column, the natural position that relates to how the flower is visited by pollinators. Curiously, to achieve this position, an orchid has to grow in a way to reposition the lip - which in its early formation is positioned on top. We call this resupination - setting the lip in a supine, or laying down, position. In the Cattleyas it happens through a twisting in the stalk (which is yet another curiosity, because it is the ovary.) Which leads to a corny ending; through a twist of fate, orchids keep their noses up in the air.
Saturday, February 7, 2009
Faux Life
Today's Los Angeles Times included a full-page article on a private garden landscaped entirely with fake plants - a concept I wrestle with. I have seen wonderful artificial plants in landscape settings, for example in the forest diaramas at the Chicago Museum of Natural History. When I used to visit the museum in the early 70's, I was astonished at Trilliums and other spring woodland flowers along with life-sized trees presented in near perfection. The purpose of these presentations was not to fool the visitor, rather to create a 3-dimensional compelling image something like a storefront - not meant to deceive but to explain. The visitor understood these were mock-ups and was allowed to marvel at the beautiful craftsmanship of each object.
Adam Issac's terrace garden, pictured in the Times, has a different purpose. It is meant to bring in play the effect of a planted patio garden without the fuss and muss of living plants. And, at least in the newspaper photos, it looks like a diarama that might be in some future anthropological museum - modeling how people lived in Los Angeles in 2009. But Issac's garden brings him comfort I am guessing, as do faux flower arrangements and weeping figs all around the country. Which is nice, I want to think. After all, this reminds us that people like the look of plants, and that plants help to finish a scene. A place just seems more inviting (I want to say "warmer") when plants deck the halls.
The dark other side of this for a botanist is the realization that many people do not quite appreciate the difference between life and faux life. Regardless how pale and unmoving a Pothos may be as it clings to existence in a dim parlor, it is alive. It is a living being, taking in water and nutrients, photosynthesizing, respiring, transpiring, growing, and eventually, dying. When newly brought to the parlor, the plant had a plastic quality, a waxy sheen of perfection. But every fresh moment (though every month is more detectable in our frame of reference) the plant is different, changing for the better or worse. And the body of this plant is fantastically more complex than that of the silk or plastic stand-in. Artificial plants are made of exuded and molded polymers, solids with integral, even color. Living beings are made of cells - for life is, basically, a cellular affair. We know there is a dynamic balance of interactions inside, through, and between cells - orchestrated to acheive self-perpetuation. At the simplest level this may be perpetuation of the individual type of cell; at the most complex level it is perpetuation of whole organisms. This means that a living plant, regardless how plastic it may appear, is made of myriad cells, cells of many kinds. Each cell is totally complex and multidimensional, with its own differently textured and subtly colored parts and pieces. Under a microscope, the cells of the greenest plant are mostly clear, with only the tiniest lozenges of green stirring about. Comparing the microscopic view of a living cell to a chunk of plastic that makes a fake plant is somewhat like comparing the workings and appearance of the most complex flatscreen TV to a sheet of plastic that is dyed and painted the same colors as a picture on the screen - but not really - because the difference is orders of magnitude greater.
Still, at a distance, faux plants can be quite deceiving and alluring. More than twice I have been fooled by them, and have always wondered about people's perceptions of artificial plants. A few summers ago I hosted a group of IEA students for two weeks. We studied many plant topics together, and made some interesting experiments. One study involved purchasing three artificial plants/flowers and three living examples that were as similar in color, shape, and size as possible. The students set up a comparison, asking visitors to select (from a distance) which of each pair was real, and which was fake. The visitors were then asked to view a sample of each specimen through a simple dissection microscope (magnification about 20x). People did pretty well with a fern, and with a Gerbera - selecting the correct one as artificial from a distance and confirming that choice when viewing through the microscope. But a Phalaenopsis orchid proved an interesting case. Visitors correctly selected the artificial specimen from a distance, but in many cases changed their minds when viewing the flower through the microscope. I believe this curious shift came about because even at 20x, the cellular structure of the live orchid flower was not obvious, its waxy petals and column looking for all the world as though they are cast from plastic. The silk specimen, on the other hand, showed its fabric nature under magnification. You could see squares formed by the fibers... hollow squares which I think the public perceived as "cells."
Nifty, and curious. The observations cause me to speculate that people know they should expect to see cells, but they have lttle idea what to expect. The crisscross patterns of fibers, easily visible, come as close as anything else to representing the textbook image of a grid of cells.
So back to the Times and the patio garden, with rules detailed by author Barbara Thornburg in her sidebar that suggest how to "do artificial intelligently." Barbara wants us to keep choices to the ecology of built spaces, which means matching the surreal to the real that is implied by the nature of the space; that is, selecting plants that might actually grow in the space. It also means maintaining a storeroom of artificial plants so the sunflowers do not make an appearance in winter, and tulips do not hang around until August. Another rule bids you take a walk in nature to observe how plants really grow. Actually, you could do that on your patio if you had live plants.
I shouldn't sound snide. I like artificial plants when cleverly used. Even Disneyland has taken to using artificial flowers in the hanging baskets on Mainstreet USA-eh-A. And I see them in yards all around Southern California. One of my particularly favorite displays is a corner home landscape near California and Michillinda, a yard that is completely paved but for a permanent border, a host of golden daffodils. It is the happy land of eternal spring. Though plastic, it is unfair to say the plants in this corner garden, other yards, and balconies over the area do not change. We may all take perverse enjoyment in the way, over the months and years, that plastic leaves and flowers age in the light of day, like tattoos, to a peculiar faded indigo. Change is in order; they are, after all, by strictest definition, organic.
Adam Issac's terrace garden, pictured in the Times, has a different purpose. It is meant to bring in play the effect of a planted patio garden without the fuss and muss of living plants. And, at least in the newspaper photos, it looks like a diarama that might be in some future anthropological museum - modeling how people lived in Los Angeles in 2009. But Issac's garden brings him comfort I am guessing, as do faux flower arrangements and weeping figs all around the country. Which is nice, I want to think. After all, this reminds us that people like the look of plants, and that plants help to finish a scene. A place just seems more inviting (I want to say "warmer") when plants deck the halls.
The dark other side of this for a botanist is the realization that many people do not quite appreciate the difference between life and faux life. Regardless how pale and unmoving a Pothos may be as it clings to existence in a dim parlor, it is alive. It is a living being, taking in water and nutrients, photosynthesizing, respiring, transpiring, growing, and eventually, dying. When newly brought to the parlor, the plant had a plastic quality, a waxy sheen of perfection. But every fresh moment (though every month is more detectable in our frame of reference) the plant is different, changing for the better or worse. And the body of this plant is fantastically more complex than that of the silk or plastic stand-in. Artificial plants are made of exuded and molded polymers, solids with integral, even color. Living beings are made of cells - for life is, basically, a cellular affair. We know there is a dynamic balance of interactions inside, through, and between cells - orchestrated to acheive self-perpetuation. At the simplest level this may be perpetuation of the individual type of cell; at the most complex level it is perpetuation of whole organisms. This means that a living plant, regardless how plastic it may appear, is made of myriad cells, cells of many kinds. Each cell is totally complex and multidimensional, with its own differently textured and subtly colored parts and pieces. Under a microscope, the cells of the greenest plant are mostly clear, with only the tiniest lozenges of green stirring about. Comparing the microscopic view of a living cell to a chunk of plastic that makes a fake plant is somewhat like comparing the workings and appearance of the most complex flatscreen TV to a sheet of plastic that is dyed and painted the same colors as a picture on the screen - but not really - because the difference is orders of magnitude greater.
Still, at a distance, faux plants can be quite deceiving and alluring. More than twice I have been fooled by them, and have always wondered about people's perceptions of artificial plants. A few summers ago I hosted a group of IEA students for two weeks. We studied many plant topics together, and made some interesting experiments. One study involved purchasing three artificial plants/flowers and three living examples that were as similar in color, shape, and size as possible. The students set up a comparison, asking visitors to select (from a distance) which of each pair was real, and which was fake. The visitors were then asked to view a sample of each specimen through a simple dissection microscope (magnification about 20x). People did pretty well with a fern, and with a Gerbera - selecting the correct one as artificial from a distance and confirming that choice when viewing through the microscope. But a Phalaenopsis orchid proved an interesting case. Visitors correctly selected the artificial specimen from a distance, but in many cases changed their minds when viewing the flower through the microscope. I believe this curious shift came about because even at 20x, the cellular structure of the live orchid flower was not obvious, its waxy petals and column looking for all the world as though they are cast from plastic. The silk specimen, on the other hand, showed its fabric nature under magnification. You could see squares formed by the fibers... hollow squares which I think the public perceived as "cells."
Nifty, and curious. The observations cause me to speculate that people know they should expect to see cells, but they have lttle idea what to expect. The crisscross patterns of fibers, easily visible, come as close as anything else to representing the textbook image of a grid of cells.
So back to the Times and the patio garden, with rules detailed by author Barbara Thornburg in her sidebar that suggest how to "do artificial intelligently." Barbara wants us to keep choices to the ecology of built spaces, which means matching the surreal to the real that is implied by the nature of the space; that is, selecting plants that might actually grow in the space. It also means maintaining a storeroom of artificial plants so the sunflowers do not make an appearance in winter, and tulips do not hang around until August. Another rule bids you take a walk in nature to observe how plants really grow. Actually, you could do that on your patio if you had live plants.
I shouldn't sound snide. I like artificial plants when cleverly used. Even Disneyland has taken to using artificial flowers in the hanging baskets on Mainstreet USA-eh-A. And I see them in yards all around Southern California. One of my particularly favorite displays is a corner home landscape near California and Michillinda, a yard that is completely paved but for a permanent border, a host of golden daffodils. It is the happy land of eternal spring. Though plastic, it is unfair to say the plants in this corner garden, other yards, and balconies over the area do not change. We may all take perverse enjoyment in the way, over the months and years, that plastic leaves and flowers age in the light of day, like tattoos, to a peculiar faded indigo. Change is in order; they are, after all, by strictest definition, organic.
Thursday, February 5, 2009
Prunus
I asked myself a question, today, that never has occured to me before. It isn't as though I've avoided thinking about the different kinds of stone fruits we keep in the genus Prunus. I worry about these trees, most particularly about how much I like them and yet how little I really know about their flowering and fruiting. At times it just seems that everything is a Prunus..., peach, cherry, almond, plum, chokecherry, apricot,,, and they almost all come in fruiting forms as well as flowering forms, in hundreds of selected cultivated varieties.
But why the name Prunus? I never worried about it, but had some simple idea that since we prune the fruit trees so heavily, maybe there was some historical relationship between being pruned and being a Prunus.... Wrong! When I bothered to look it up, it seems that prunus is the ancient Latin name for plum trees, prunum is a plum. And we find that the dried fruit called a prune is made from plums, most usually from cultivars of the European native plum called Prunus domestica. But the verb "to prune" has its origins somewhere alongside the Old French action verb "proignier." I don't know how the words came together, but can't help but imagine that it makes sense for prunes to get pruned rather than to get proined.
There are other etymological confusions in the group. The peach, thought to be native to China (where it is an ancient symbol of immortality), has the scientific name Prunus persica - meaning that Linnaeus (who gets credit for the first several thousand approved plant names) associated the peach with Persia (Iran). And the common names are, as usual, a mess. A well-known plant from Europe, Prunus laurocerasus, has leathery evergreen leaves and is commonly called Cherry Laurel. Another evergreen tree, Prunus caroliniana (native to the Eastern US) is also called Cherry Laurel, though we are finding the common name Carolina Laurel Cherry becoming more common every day. Of course, neither tree (nor any rose relative) can rightfully be called a Laurel - that is a totally different group of plants.
When I talk with people about the Rose family, and the fact that Prunus is of that clan, it is hard to sell this relationship if the only proof I have is the fruit. When in flower, the tale is different. People readily see the relationship between plum flowers and those of their relatives - the apples,quinces, roses, strawberries, and spiraeas. The fruit, though, are distinctly different because unlike most other roses, the flowers produce only one pistil, which means the fruit has only one "pit" - and that pit is a stony wall that surrounds the seed. Curiously we find that this stoney surround is really the inner layer of the otherwise soft, fleshy fruit. Which leaves us with one more word. A fruit that has a soft outer layer, and a hard inner layer (that protects the seed) is termed a "drupe." So a plum is a drupe, as is a cherry and a peach. But a rose is a rose is a rose.
But why the name Prunus? I never worried about it, but had some simple idea that since we prune the fruit trees so heavily, maybe there was some historical relationship between being pruned and being a Prunus.... Wrong! When I bothered to look it up, it seems that prunus is the ancient Latin name for plum trees, prunum is a plum. And we find that the dried fruit called a prune is made from plums, most usually from cultivars of the European native plum called Prunus domestica. But the verb "to prune" has its origins somewhere alongside the Old French action verb "proignier." I don't know how the words came together, but can't help but imagine that it makes sense for prunes to get pruned rather than to get proined.
There are other etymological confusions in the group. The peach, thought to be native to China (where it is an ancient symbol of immortality), has the scientific name Prunus persica - meaning that Linnaeus (who gets credit for the first several thousand approved plant names) associated the peach with Persia (Iran). And the common names are, as usual, a mess. A well-known plant from Europe, Prunus laurocerasus, has leathery evergreen leaves and is commonly called Cherry Laurel. Another evergreen tree, Prunus caroliniana (native to the Eastern US) is also called Cherry Laurel, though we are finding the common name Carolina Laurel Cherry becoming more common every day. Of course, neither tree (nor any rose relative) can rightfully be called a Laurel - that is a totally different group of plants.
When I talk with people about the Rose family, and the fact that Prunus is of that clan, it is hard to sell this relationship if the only proof I have is the fruit. When in flower, the tale is different. People readily see the relationship between plum flowers and those of their relatives - the apples,quinces, roses, strawberries, and spiraeas. The fruit, though, are distinctly different because unlike most other roses, the flowers produce only one pistil, which means the fruit has only one "pit" - and that pit is a stony wall that surrounds the seed. Curiously we find that this stoney surround is really the inner layer of the otherwise soft, fleshy fruit. Which leaves us with one more word. A fruit that has a soft outer layer, and a hard inner layer (that protects the seed) is termed a "drupe." So a plum is a drupe, as is a cherry and a peach. But a rose is a rose is a rose.
Tuesday, February 3, 2009
Spectacular New Camellias
On Sunday I made a trip to Nuccio's Nursery (up in Altadena, right against the mountains above Pasadena, California), which is one of the most incredible Camellia nurseries to be found in North America. It's run by the three boys - Juge, Jim, and Tom - cousins and brothers in various combinations - and sons of the nursey's founders. If you have never visited Nuccio's, you should make a trip while Camellias are still in season. If you have visited before, let this be a reminder to go and get your annual fix - both of Camellias (and Azaleas) and of friendly, downhome horticultural expertise.
My problem in visiting Nuccio's is the sheer temptation to purchase a load of Camellias. I have never left the nursery empty handed, and sometimes have had to ask for a delivery because the haul would not fit in the pickup. That day, I only picked out fourteen plants. There were the eight handsome and somewhat dwarfish plants of 'Buttermint', each loaded with creamy white raggedly informal double flowers. I wasn't sure exactly where they would go in the garden, but was convinced that a small mass planting would make me and many other people very happy. And then there were two plants of 'Koto-No-Kaori' as well as one of 'Manato-No-Akebono' - both sasanqua-looking plants with modestly-sized but incredibly fragrant single pink flowers. 'Koto-No-Kaori' is my favorite, producing the most remarkable perfume, defying every charge that Camellias require tea olive or some other surrogate to bring fragrance to the garden.
But the spectacle of the day came from my first encounter with a pair of cultivars that Juge suggested I check out - 'Sinritsu-Ko' and 'Kino-Sinritsu'. 'Sinritsu-Ko' is the 'Peace' rose of Camellias - a loose semi-double creamy yellow with a blush of pink airbrushed onto petals that, for all the world, make the flower different from any other Camellia I have seen. There is something about the way the petals are presented, and their shape with the redoubled leading margins that is distinctly abnormal for a Camellia and completely normal for a Rose. Paired with 'Sinritsu-Ko' is a pure yellow version, 'Kino-Sinritsu', which I may like even better. Needless to say, I left with one of the pure yellow and a couple of the blushed version, wondering whether I shouldn't have bought more just for insurance. I can't wait to see how these Camellias, new to me, the novice, perform in the garden, or hold up as cut flowers. If they score well in either regard, then 'Sinritsu-Ko' and 'Kino-Sinritsu' have a wonderful future in Southern California.
Check back with me on these plants. I'd like to find out more about them..., what the names mean, and who made the selections and introductions. Stay tuned and I will let you know what I learn...
My problem in visiting Nuccio's is the sheer temptation to purchase a load of Camellias. I have never left the nursery empty handed, and sometimes have had to ask for a delivery because the haul would not fit in the pickup. That day, I only picked out fourteen plants. There were the eight handsome and somewhat dwarfish plants of 'Buttermint', each loaded with creamy white raggedly informal double flowers. I wasn't sure exactly where they would go in the garden, but was convinced that a small mass planting would make me and many other people very happy. And then there were two plants of 'Koto-No-Kaori' as well as one of 'Manato-No-Akebono' - both sasanqua-looking plants with modestly-sized but incredibly fragrant single pink flowers. 'Koto-No-Kaori' is my favorite, producing the most remarkable perfume, defying every charge that Camellias require tea olive or some other surrogate to bring fragrance to the garden.
But the spectacle of the day came from my first encounter with a pair of cultivars that Juge suggested I check out - 'Sinritsu-Ko' and 'Kino-Sinritsu'. 'Sinritsu-Ko' is the 'Peace' rose of Camellias - a loose semi-double creamy yellow with a blush of pink airbrushed onto petals that, for all the world, make the flower different from any other Camellia I have seen. There is something about the way the petals are presented, and their shape with the redoubled leading margins that is distinctly abnormal for a Camellia and completely normal for a Rose. Paired with 'Sinritsu-Ko' is a pure yellow version, 'Kino-Sinritsu', which I may like even better. Needless to say, I left with one of the pure yellow and a couple of the blushed version, wondering whether I shouldn't have bought more just for insurance. I can't wait to see how these Camellias, new to me, the novice, perform in the garden, or hold up as cut flowers. If they score well in either regard, then 'Sinritsu-Ko' and 'Kino-Sinritsu' have a wonderful future in Southern California.
Check back with me on these plants. I'd like to find out more about them..., what the names mean, and who made the selections and introductions. Stay tuned and I will let you know what I learn...
Saturday, January 31, 2009
Thorns, Spines, and Prickles
Brushing by a succulent with a spiny trunk this week, I noticed that an interpretive sign said the spines were actually modified stems. That seemed wrong, and it turned out (at least to me) the claim was faulty. In my way of defining words, any sharp plant part that is called a spine has to have been formed in the same way that leaves (and stipules) form. Therefore, cactus "spines" are rightly called spines - because they grow from the same tissues and in the same position as leaves would form, if the cacti made normal leaves. If a pointed plant part is formed by a stem tip that hardens into a sharp spike, then to me this should be called a thorn. Stems grow differently from leaves, and actually form leaves as temporary appendages, thus stems that grow to become hardened, pointed spikes are very different in origin from spines - though the resulting damage might be the same.
The most amusing fallout of adopting precise, origin-based definitions for pointed plant parts is that the sharp, recurved things we call rose thorns are not thorns at all, because they are not formed by stem tips or side branches. Moreover, they do not originate in the same manner or position as leaves, which means they are not spines either. To me, and most botanists, the sharpnesses on roses should be called prickles. That is because prickles are made by a plant in the same way that bark forms. Prickles grow from the outer layers of stem tissue, and can be snapped off without tearing into veins or other tissues that form inside stems and leaves. They begin as tiny flecks of new bark in the outer stem layers, each fleck pushing the tip outward from a widening base. If you check out a rose stem, you can see that the prickles form all around and along the stem, not at all in the predictable pattern you expect from leaves and side branches. Other plants, like Chorisia speciosa and Caesalpinia cacalaco, make bark in the shape of prickles; as the stems grow older and broader they continue to generate more prickles that sometimes merge into more solid patches of bark.
Back to the succulent I brushed against, a Pachypodium. The spines form along the trunk, but they form in a very regular and predictable pattern that has nothing to do with bark. They can always be found in pairs, a ready clue to the fact that they are the sharp and hardened evidence of stipules, which are bits of foliage that form at the base of leaves in some kinds of plants. Stipules are considered to be leaf tissue because they originate as part of the leaf, which means that any stipules that become pointed and hard would also be considered spines. We see these paired "stipular spines" in many other plants, most notably the Crown of Thorns Euphorbia.
Oddly, because they are scattered along the stem, the similarity to rose thorns cannot be ignored. But the difference is real and significant, when you consider origin.
So why the spines, in this case? And why prickles or thorns in others? We can see obvious ways that succulents in drylands and deserts might benefit from the pure mechanical protection of dagger-like parts. But we know very little about the life histories and ecologies of individual kinds of spiny succulents, so we are left with the generalization that spines, thorns, and prickles give desert plants an upperhand in conserving some of the hard-earned water they hoard agains even harder times.
And why should we care to discriminate between a spine, a thorn, and a prickle? To me these words have meaning, metadata, that helps tell the story of how plants grow and develop. It is a brush with comparative morphology, when the word homology reminds us that studying the common origin of differently appearing organs allows a richer appreciation of adaptation and evolution.
The most amusing fallout of adopting precise, origin-based definitions for pointed plant parts is that the sharp, recurved things we call rose thorns are not thorns at all, because they are not formed by stem tips or side branches. Moreover, they do not originate in the same manner or position as leaves, which means they are not spines either. To me, and most botanists, the sharpnesses on roses should be called prickles. That is because prickles are made by a plant in the same way that bark forms. Prickles grow from the outer layers of stem tissue, and can be snapped off without tearing into veins or other tissues that form inside stems and leaves. They begin as tiny flecks of new bark in the outer stem layers, each fleck pushing the tip outward from a widening base. If you check out a rose stem, you can see that the prickles form all around and along the stem, not at all in the predictable pattern you expect from leaves and side branches. Other plants, like Chorisia speciosa and Caesalpinia cacalaco, make bark in the shape of prickles; as the stems grow older and broader they continue to generate more prickles that sometimes merge into more solid patches of bark.
Back to the succulent I brushed against, a Pachypodium. The spines form along the trunk, but they form in a very regular and predictable pattern that has nothing to do with bark. They can always be found in pairs, a ready clue to the fact that they are the sharp and hardened evidence of stipules, which are bits of foliage that form at the base of leaves in some kinds of plants. Stipules are considered to be leaf tissue because they originate as part of the leaf, which means that any stipules that become pointed and hard would also be considered spines. We see these paired "stipular spines" in many other plants, most notably the Crown of Thorns Euphorbia.
Oddly, because they are scattered along the stem, the similarity to rose thorns cannot be ignored. But the difference is real and significant, when you consider origin.
So why the spines, in this case? And why prickles or thorns in others? We can see obvious ways that succulents in drylands and deserts might benefit from the pure mechanical protection of dagger-like parts. But we know very little about the life histories and ecologies of individual kinds of spiny succulents, so we are left with the generalization that spines, thorns, and prickles give desert plants an upperhand in conserving some of the hard-earned water they hoard agains even harder times.
And why should we care to discriminate between a spine, a thorn, and a prickle? To me these words have meaning, metadata, that helps tell the story of how plants grow and develop. It is a brush with comparative morphology, when the word homology reminds us that studying the common origin of differently appearing organs allows a richer appreciation of adaptation and evolution.
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