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.