From the pages of Kitchen Gardener Magazine

Understanding Plant Names,
or The Importance of Being Botanical

To know a plant's taxonomy is to know its disposition and habits, its likes and dislikes, its friends and enemies

by Cass Peterson

If I were given a packet of seeds labeled with the botanical name Phaseolus coccineus, I would know that there was a bean involved, as well as the color red. In the time of Cicero, phaselus was a light boat, similar to a canoe and shaped like, well, like a bean pod. Coccineus means scarlet-colored, from "coccum," the berry of the scarlet oak, used as a dye by the ancients.

Hence, Phaseolus coccineus means red bean -- descriptive enough, although not as precise as the common name in English, scarlet runner bean.

How important is it to know a plant's botanical, or Latin, name? A bean by any other name will grow as well; a Cucumis melo, Reticulatus Group, will smell and taste as sweet if you erroneously call it a cantaloupe instead of a muskmelon.

But to know a plant's taxonomy is to know its family -- its disposition and habits, its likes and dislikes, its friends and enemies.

Names are knowledge
As important as knowing that Phaseolus coccineus will produce red beans is knowing that it is a member of the Leguminosae, the legume family, along with around 12,000 other species that are capable of producing their own nitrogen from the air. Knowing this, I do not squander my richest soil on or apply too much fertilizer to scarlet runner beans.

Because my broccoli, kale, cabbage, kohlrabi, and Brussels sprouts all belong to the Cruciferae, or mustard family, I can safely assume that they have similar growing requirements: full sun, high fertility, plenty of water, a soil pH as close to neutral 7.0 as possible. All will withstand cold weather at either end of the growing season, and all dislike the hot weather in the middle. All, alas, are attractive to flea beetles and cabbage worms.

If I decide to try a new Asian vegetable in the mustard family, I may not know how to cook it, but I'll have a good idea how to grow it. I already know its family habits.

The Swedish botanist Linnaeus is generally credited with establishing the modern binomial system of plant names, which involves a genus name and a species name. Phaseolus is the genus of annual beans with edible seeds or pods; coccineus further defines the species scarlet runner bean.

Genuses, however, belong to larger family groupings, like Leguminosae, Cruciferae, or Solanaceae (the nightshade family, which includes tomatoes, eggplants, potatoes, and peppers). There are hundreds of edible plants in the Labiatae or mint family (mint, of course, and basil), the Compositae or sunflower family (lettuce, endive, Jerusalem artichokes), the Amaryllidaceae or amaryllis family (onions, garlic), and the Chenopodiaceae or goosefoot family (spinach, beets, chard).

Even plant groups grown mostly as ornamentals may have a munchable member or two, like the mallow family's Abelmoschus esculentus, or okra. A solid clue to edibility is the species name esculentus (or a variant, like esculentum). In Latin, it means edible.

Plant form suggests identity
If you're not certain of a plant's family, you can often identify it by looking for a habit or appearance it has in common with other plants in your garden. For example, the term Cruciferae refers to the cross-shaped flower common to members of the mustard family. Without knowing the botanical name of common winter cress (Barbarea vulgaris), I can place it with the mustards by looking at its cross-shaped yellow flowers. I see the same flower on bolting bok choy and broccoli.

Members of the Umbelliferae, or carrot family, share umbrella-shaped flower clusters, like the dill heads you use in pickling. Other members of the family, including parsley, cilantro, and celery, have the same flower form.

A plant's full pedigree starts with its membership in the plant kingdom rather than the animal kingdom. From there, taxonomists apply ever more rigorous classification tests. Consider the eggplant. Its division of the plant kingdom is spermatophyte, meaning that it doesn't produce by simple cell division, and that it produces seeds rather than spores. Further, it's assigned to the class angiospermae, which means it is a flowering plant. Its subclass of angiospermae is dicotyledonae, which means that two seed leaves, not one, sprout from its seed.

Its order is Solanales, a grouping of families that have both male and female organs in five-petaled flowers and share some other characteristics, like alternate leaves and foliage that has a scent.

Most popular taxonomy guides kick in at the next level down: family. Eggplant's family is Solanaceae, the nightshade family. The genus is Solanum, a broad grouping that includes a bunch of strictly ornamental plants like African holly and some poisonous plants like common nightshade and Jerusalem cherry.

Eggplant's species is melongena. The name is a corruption of the Latin malainsana, or mad apple, an unsavory reputation eggplant got from its close association with all those toxic nightshades. But Solanum melongena is further divided into the subgrouping esculentum (aha! edible!).

That's the end of the botanist's job (see How a taxonomist describes eggplant), but horticulturists add another category, called cultivar (for CULTIvated VARiety), such as 'Black Beauty', and all the other luscious-looking fruits that peek out from the pages of the seed catalogues.

Even though plants don't change their habits, taxonomists occasionally change their names, causing some confusion among nonprofessional plant people. The official rule book is the International Code of Botanical Nomenclature, which gets updated periodically at an international conference of botanists, the most recent in Tokyo in 1994.

By the book, the family Cruciferae is now officially Brassicaceae (brassica is cabbage in Latin), Leguminosae is Fabaceae (faba in Latin refers to the broad or fava bean), and Umbelliferae is Apiaceae (a reference to the bee-attracting properties of the flowers). The new names, like the old, mean something. But the old names are still considered correct, and you can use them if you prefer. As I do. A bean by any other name may still provide its own nitrogen, but the legume in Leguminosae makes it easy to remember.

Cass Peterson contributes frequently to the Cuttings column in The New York Times.

Photo: Marc Vassallo

From Kitchen Gardener #26, pp.49-50
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