Plant Classification

Plant Traits and Terminology

Plant Family Practice “Game”

Picture of Flower Parts As we go on field hikes in Biology Lab, you will be learning to identify many of the local plants and animals. For many of the plants we find, we will also discuss in what plant family those plants are classified. You will be expected to sight-identify these plants to family, based on knowing and recognizing key characteristics of the families to which they belong. You may also be expected to sight-identify new, unfamiliar plants to family based on their characteristics.

To a biologist, the words “plant” and “flower” have very specific and different meanings. A flower is a specialized reproductive structure which develops on plants in the Angiospermae. In most cases, it is technically incorrect to say that you have planted “flowers” in your garden (unless you buried the wilted, cut roses a friend gave you a month ago), and in general, the result of that would be compost. However, to say that you put “plants” into your garden so you could enjoy the flowers they produce is an appropriate statement. Note that both maple trees and marigolds are plants, and both produce flowers. Throughout this discussion, the word “flower” will be used to mean a flower, not a plant.

Picture of Flower Arrangements Plants are typically grouped into families based on similarities in their structures. The type(s) and organization of the flower parts are often key traits by which plant families may be determined. Thus, botanists, have come up with a scheme for representing the flower structure of the various families. Botanists represent the parts of flowers and arrangement of those parts using the following notation.

In this notation, a horizontal line is used to represent the receptacle, thereby indicating which parts are attached above or below the receptacle. The area of the stem just below the receptacle is called the pedicel. The following symbols are used to represent other flower parts.

Sample Plant Formula These symbols may be combined, as needed, to represent the structure of a given flower. For example, the formula to the right means that in this particular flower, there are five free sepals, five united petals, five free, epipetalous stamens, an inferior ovary with two united carpels, and the type of fruit is a capsule. Here, then, are descriptions of some of the main families of plants.

Selected Plant Families

Some Further Terminology:

Copyright © 1998 by J. Stein Carter. All rights reserved.
Chickadee photograph Copyright © by David B. Fankhauser
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