Abstract: A plant seed begins with a single cell, called a zygote. You, a human, started as a zygote too. And your first cell, just like the one that is a plant zygote, was formed when a sperm nucleus joined an egg. The saga of how that single cell (the zygote) becomes a seed, and how that seed grows up and makes its own sperm and eggs is the life story of each generation - what we call the life cycle.
But the life cycle of plants is more embellished than ours. Plants have a secret life that plays out before our very eyes, hidden in plain view. To appreciate this extra bit of complexity, you must get past some bothersome but simple math. Plants and humans function with two sets of chromosomes. To reproduce sexually, those chromosomes must be reduced to a single set, not halved in a willynilly way, but reduced to a single matching set (we call this a single complement, designated by the letter "n" because different organisms have a different number in the complement.) This single complement is all of the chromosomes an egg or a sperm will need. It is the recombining of sets, an egg from your ma and a sperm from your pa, that brings two sets back to the party, two sets for the new generation - which is you. If that makes sense, then you are ready to work through the following tale.
The Story: It is a great word - zygote. It is the essence of beginning, the name we use for the first cell of a new generation. Formed by the union of sperm with egg, the zygote magically re-sorts and restores the full genetic complement necessary to operate most of the plants around us.
I was thinking about the idea of a zygote because that is where I began a botany class the other day for Yvonne Savio's Los Angeles County Master Gardener trainees. It just seemed like the right place to jump into the story of plant life cycles because the green flowering plants that make up the flora of our vegetable gardens all began their current generations as zygotes.
Beginning discussion with this diploid (having two sets of chromosomes) cell belies its recent history. Each zygote is a new being, a new combination of life with two sets of chromosomes that resulted from sexual union. Sex, by this narrow half-definition, happens when the two famous gametes, a sperm and an egg, join. In reality, the joining itself is fairly ignominious. The male pollen tube basically dumps a nucleus into the egg cell. But that comes after some serious travail, is the product of some serious limitations, and (of course) is just the headliner; many other things happen that are as crucial.
Going backward we get to these curious gametes, the sperm nucleus and egg. Like Voldemort, the egg and the sperm are no longer whole. They are simply the final products of a frail and arcane generation that lived a kept-life with only a single set of chromosomes - a haploid life. Yes, between one pumpkin and the next generation of pumpkin live these arcane, horcrux-like haploid beings which botanists call "Gametophytes" - so named because these are the plants that create the gametes (sex cells) we call sperm and egg. But they are so unseen as to be nearly unheralded.
The Male Gametophyte is the easier to envision of the two kinds. It is the pollen grain, which eventually becomes a free-living, free-ranging, speck-like non-green plant with only one set of chromosomes (the condition we call haploid.) When grown up, it has two or three nuclei. The egg belongs to a similarly haploid plant that you will never see, all tucked inside an ovule in a flower pistil (eventually a pea in a pod.) Though hidden, the Female Gametophyte has a much more exhuberant life than the pollen grain. It grows up to become what we call an embryo sac, a microscopic, haploid "plant" with several nuclei (often 8), one of which is "the egg."
So where did these Male and Female Gametophytes come from? As Harold Bold (who studied plant morphology at The University of Texas and at Vanderbilt University) would have taught you, they came from spores - little haploid spores. In their flowers or cones, the "normal", Diploid plants make special haploid spores through a curious kind of cell division called meiosis. Meiosis is every bit as dramatic as the process by which Voldemort split his soul, except it is real. And it happens millions of times a day all around you, in special cells in anthers and pistils of flowers and in the scales of cones. To make pollen grains, special cells each divide and turn out four little, equal-sized microspores - each of which now has one set of chromosomes. In the pistil, those special diploid cells divide unevenly; producing four haploid cells, but three will be failed, empty cells and one will be a larger megaspore that (along with its single set of chromosomes) gets all of the cell content. A microspore grows up to be a pollen grain. A megaspore grows up to be an embryo sac. Since it is the Diploid plants that make these microspores and megaspores, Botanists call them Sporophytes. As a sidebar, this is also how we decide what to call male and what to call female. When there are two different products of meiosis in a life cycle, the spores portioned out as four equally sized and active cells (the microspores) are considered "male" - while the single megaspore that was invested with all of the original cell contents is "female."
The implication of these even and uneven divisions is profound. Having preferentially received all of the cell contents, the embryo sac (now the Female Gametophyte because it will produce the female gamete) has more than a nucleus, it has all of the other stuff a normal plant cell needs in its cytoplasm (mitochondria, plastids, membranes, etc.) The egg (which is the female gamete, the "sex cell") therefore brings everything to the party - a nucleus with a single set of chromosomes as well as the other structures and genetics a plant cell needs to function. The male spore began as a smaller cell in the first place, which became a pollen grain. The pollen grain lands on a stigma and grows its pollen tube to the embryo sac- but in the end, it delivers only its nucleus to the egg, only its set of chromosomes. The result is what we call "maternal inheritance." Characteristics derived from structure and genetic information in various components of the cytoplasm came with the egg, the female parent. That can be curiously important; both chloroplasts and mitochondria are in this camp, reproducing themselves from plastids that are part of the cytoplasm - not from genetic information carried in the nuclear chromosomes.
So the real beginning of sex is meiosis. In plants, this first half of sex yields spores that have their own, frail but modestly exhuberant lives before producing the sex cells, the gametes. The end of sex becomes the union of sperm nucleus and egg nucleus (which we call syngamy.) Thus we sometimes talk about plants as showing "alternation of generations" - from diploid normal beings to half-hidden haploid plants (from Sporophyte to Gametophyte,) before being "restored" as a new generation of diploid plants. For humans the alternation does not apply. In human males, meiosis yields four cells which are themeselves the gametes, the sperm cells. In human females, meiosis yields a single well-outfitted cell called the egg (while discarding the other three haploid sets of chromosomes.) Humans go straight from diploid cells to egg and sperm, the gametes that unite right again to make new zygotes.
Starting with the zygote can be a good beginning for a lecture, but it is just one point in the great progression of life - bearing heavily on the question of when life begins. Life does not start with a zygote, it does not begin with a single cell, because life never ended. The sperm and egg are as alive as the zygote - they are frail and totally dependent - you may call them helpless, or you may think of them as parasites. But they are a crucial link in the chain of life, carrying all of the genetics and structure and life processes that characterize living things. What we might call new "lives" are simply the most recent diploid beings that were generated by this remarkable sexual system. But "life" itself doesn't really "start" because it never ends. Breaking the chain of life is not merely death, it is extinction.
Sunday, May 2, 2010
Saturday, June 6, 2009
A Fragrant, Monoecious Flower
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.
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.
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.
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