New Wondrium Series Divulges the Language of Botany

botanical terminology explored from root to leaf

By Jonny Lupsha, Wondrium Staff Writer

Plant terminology goes far beyond roots, stems, and leaves. Each are classified into multiple categories based on physical characteristics and growing seasons. If you don’t know a trichome from a petiole, we’ve got you covered.

red poppy flowers in field
Although most plants can be identified by their descriptions in identification books, some have unique characteristics such as behaving like annuals in cold climates and perennials in milder climates, as is the case with poppies. Photo by Nitr / Shutterstock

Whether you’re a veteran home gardener, an aspiring floral design champion, or just a person who doesn’t want to kill the houseplant you got as a present, the world of botany involves tips, tricks, and tools of the trade. One of the most valuable tools in plant life is language.

For example, grasses and herbs have herbaceous stems, while trees and shrubs have woody stems. Stem types tell botanists about the plant’s growth forms, or its overall morphology. Seemingly insignificant characteristics like these, or the shapes of plant roots, help botanists identify different plant species and, thus, learn how to care for them.

What are the most important terms in botany? In her video series The Botanist’s Eye: Identifying the Plants around You, Dr. Catherine Kleier, Associate Dean of Faculty in the College of Agriculture, Food, and Environmental Sciences at California Polytechnic State University, analyzes the language of botany.

Annuals vs. Perennials

How does one identify a plant type? Flowering plants can offer a helpful clue.

“Many identification books will ask whether the plant is annual or perennial,” Dr. Kleier said. “Annuals usually flower from spring melt to first frost, which is more true in the garden than in the field, but this is still a useful guideline. In the field, many annuals will bloom when there is adequate water, such as many desert annuals.

“In fact, some plants will behave like annuals in cold climates but perennials in milder climates, such as poppies.”

What is a perennial? According to Dr. Kleier, perennials have much shorter flowering times. Perennials flower in two to three weeks, but they come back the following year. Another tip for identifying perennials is that any flower with a woody stem is a perennial, while plants with herbaceous stems—or flexible, green stems—can either be annuals or perennials.

To put it another way, when a plant has a flexible, green stem, we have to look elsewhere to determine if it’s an annual or a perennial, such as recording its flowering time. If it has a woody stem, we can save ourselves some time because we know it’s a perennial.

Make like a Tree and Leave

Another way to narrow down what kind of plant you’re looking at is by checking its leaves, where, according to Dr. Kleier, a lot of the identification takes place.

“For many broad-leaved trees, the shape of the leaf and the texture of the bark are the main identification characteristics,” she said. “Broad leaves mean that the leaves are broad and this is usually contrasted with needle-like, such as conifers. Leaf shape is best for defining species.”

To define a family, botanists look to the arrangement of leaves on a stem. Dr. Kleier said that the location where a leaf inserts into the stem is called the node, while the leaf stem itself is called the petiole. The way that the petiole attaches to the stem determines the leaf arrangement, of which there are three kinds.

“An opposite leaf arrangement occurs where one leaf inserts directly opposite a leaf on the other side of the stem,” she said. “This is in contrast to an alternate leaf arrangement, where leaves—you guessed it—alternate up the stem. The third type of leaf arrangement is called whorled. Whorled means that the leaves are arranged in a circle around the stem—think a whirl or whorled leaves.”

Learning to differentiate between stem types, leaf arrangements, and annuals vs. perennials goes a long way in unlocking the mysteries of the plant life in our world.

The Botanist’s Eye: Identifying the Plants around You is now available to stream on Wondrium.

Edited by Angela Shoemaker, Wondrium Daily