Botany for the Bewildered

In one day I read scientific names for plants used on two of my favorite gardening blogs (La Gringa’s Blogicito and Gardener in Chacala, Mexico). La Gringa talked about finding foliage plants – the kind we used to grow as house plants in the US – by the side of the road. She listed the scientific names of three of them. The Mexican gardener talked about learning how the Prickly Pear, Opuntia ficus-indica, can be used as a medicinal plant. (Since then, she’s posted several more scientific names of flowers!)

I was chagrined. Here I am struggling to learn the family name of any particular plant that I collect, and there they were, on that day, spewing out genus and species names. Sigh.

It reminds me of the time several years ago that a friend of mine, a professional botanist, tried to teach me how to recognize members of the rose family (5 petals, 5 sepals is all I remember from that session). But when she showed me another sample of a member of the rose family, I blanked on what I had already learned. What a failure! At that time I could distinguish with ease the microscopic features of marine crustaceans, but put a plant in front of my face and….well.

But I’m gaining courage. A new book arrived in the mail: A Field Guide to the Families and Genera of Woody Plants of Northwest South America (Columbia, Ecuador, Peru) by Alwyn H. Gentry. The author asserts that the families of tropical plants are actually easy to learn. He’s provided keys to identification that look encouragingly straightforward to use. So maybe it will happen.

I’ve been wondering why it is so important to me to get the name of a plant right.

Way back in high school biology we learned that the scientific name is important because everyone in the world uses the same scientific name for a certain living creature – plant, animal, fungus, whatever – and so you can be sure you’re talking about the right plant when you’re talking to someone who lives in an area other than yours. Now with such easy access to the internet, it’s also useful to use the scientific name if you want to find medicinal or other commercial uses of plants. Also, if you want to buy the right plant for your garden!

But my desire to get the name right goes deeper than that. I think it comes from some need for order, and I’m certainly not the only human being who feels this way. The entire field of taxonomy is devoted to classifying living things based on how closely related to each other they are.

If you look up the scientific name of a plant on Wikipedia, you get the full scientific classification over on the right hand side of the article. When I do a search for Byrsonima crassifolia, say, (the scientific name of the nance tree) here’s the classification scheme:

Scientific classification

Kingdom:Plantae
Division:Magnoliophyta
Class:Magnoliopsida
Order:Malpighiales
Family:Malpighiaceae
Genus:Byrsonima
Species:B. crassifolia

Binomial name
Byrsonima crassifolia
(L.) Kunth

Starting at the top and working down: The Kingdom is a high level of classification – there is a kingdom for plants, one for animals, one for fungi, and a couple of others depending on whose classification scheme you use. For most of us mortals, distinguishing between plants and animals is all we need to do on a practical level. Kingdom Plantae has an -ae ending. Kingdom Animalia has an -ia ending. I’d better ask my nephew, a Latin scholar, why this is so.

A Division of plants is roughly equivalent to a Phylum of animals. At the Division level we distinguish between the conifers (Pinophyta) and the flowering plants (Magnoliophyta) among other groupings. Notice the -phyta ending.

At the Class level we distinguish between flowers (Magnoliopsida -in high school biology we learned these were dicotyledons, the ones with 2 seed leaves) and grasses (Liliopsida – the monocotyledons, the ones with only one seed leaf). Note the -opsida ending.

Starting with the Order level we are narrowing down our massive classification from all of dicotyledons to a group of more closely related plants. There is no longer any allusion to magnolias at this point. The nance tree is in a different order, an order named after an early botanist , Marcello Malpighi, who is best known for his work on microscopic anatomy. The Malpighi layer of skin is named after him, as are the Malpighian corpuscles in the kidneys. His work on botany, Anatomia Plantarum, was published in 1671. Note the -ales ending for Order names.

At the Family level we find plants that are even more closely related, and we start to see some geographic connections. Plants of the Malpighiaceae family (named after the same guy) are found in the tropics and subtropics, and most of these are in the New World. Here’s a glossed-over (by me) ending: -aceae.

Families of plants are so closely related that, according to Thomas J. Epel of Botany in a Day, you can nearly always predict medicinal or other properties of a plant if you know its family. The Malpighiaceae family contains the genus Malphighia and in that genus is the Acerola plant, Malpighia glabra. From this I would suspect that the fruit of the nance tree is relatively high in vitamin C! Worth checking out, anyway.

Under families, we have Genus and Species names. The plants are getting more and more closely related. Traditionally, living organisms of the same species can breed with each other but not with members of other species. Closely related species are placed in the same genus. Together, the genus and species names comprise the scientific name of a plant. Because two words are used for the name, the scheme is called “binomial classification.”

The correct way to use genus and species names is to capitalize the genus name, keep the species name in lower case, and italicize both. Thus, the scientific name for the nance tree is Byrsonima crassifolia. Finally, you often see a non-italicized name after the scientific name. This is the name of the person who first described the plant in detail and gave it a name.

About that sense of order – simply going through this exercise has helped me get my thoughts together about the grand scheme of things in the plant world. I know that from now on I’ll be concentrating on learning the features that help distinguish families, but it’s useful to know the higher relationships. Once I get a few families under my belt, then it will be onwards to genera (the plural for genus). Oh, and by the way, the singular for “species” is “species,” not “specie.” Just a little irritant I run into now and then.

Which brings me back to the gardeners mentioned at the beginning of this post. They both used scientific names correctly – italicized, with the genus capitalized and the species in lower case. Very satisfying to see.

However, the last word must come from Darwin. [At the link, scroll to the bottom of the page to see the quote.]

“I am strongly induced to believe that as in music, the person who understands every note, if he also possesses a proper taste, more thoroughly enjoy the whole, so he who examines each part of a fine view, may also thoroughly comprehend the full and combined effect.  Hence, a traveler should be a botanist, for in all views plants form the chief embellishment.”  Charles Darwin, The Voyage of the Beagle