From Seed to Seed:
Plant Science for K-8 Educators

Terminology: Genus and Species

Let's begin by discussing what is meant by the terms genus and species. An easy way to remember these terms is to note that genus refers to the "generic" name, and species refers to the "specific" name.

The species name is the basic unit of classification. It describes one kind of plant within the genus, and is almost always an adjective. By itself, the species name is meaningless. For example, Digitalis purpurea is the botanical name for foxglove, while Echinacea purpurea is the name for purple coneflower. The species name, purpurea, tells us that some part of the plant is purple but by itself gives no indication of the identity of the plant.

Sometimes the meaning of a Latin name is fairly obvious-for example, biennis means biennial. However, many other not-so-obvious species names apply to familiar plants. Knowing their meaning can help you remember the name-and give you some clue about the characteristics of the plant. See the Appendix for a list of Latin words frequently used in species names and for a simple activity to conduct with students.

What criteria are used to separate individual species? This is a difficult question to answer precisely. Generally speaking, a species is a type of plant having certain characteristics that differentiate it from other members of the genus, and retaining these distinctions through successive generations. Individuals of different plant species often cannot interbreed-although, unlike in the animal kingdom, this is not a reliable criterion for defining a species in the plant world.

Information on the thousands of plant groups and hundreds of thousands of species continues to accumulate. As a result, plant classifications are sometimes modified to reflect new information about plant relationships. In addition, it is often up to individual botanists to determine when a group of plants is different enough from others in the genus to constitute designation as a unique species.