Horticulture 202 Laboratory 3


How to Write a Scientific Name

Practice Writing a Scientific Name

What is a Key?

Rules For Using a Key

Sample Key

Key Tutorial

Horticultural Sites


What is a Key?

A key is a tool used for identifying plants. Using a key to identify a plant is referred to as "keying out" a plant. Dichotomous (forking) keys are usually used. These types of keys are composed of successive choices between two contrasting statements called couplets. The couplets are usually denoted by the same number or level of indentation.

1. Plant with broad leaves. . . . . . . . .2
1. Plant with needle-like leaves. . . . . .Pinus sp.

While studying the plant sample, you will read both statements (the couplet). You will then choose the correct or most correct statement. The statement you choose will instruct you to proceed or will provide a plant name.

If the first statement in the couplet above is correct, move on to the second statement.
If the second statement in the couplet above is correct, you may be looking at a species of pine.
Think of a using a key as being analogous to traveling down a multi-forked road. To get to your final destination, the correct choice must be made at each fork. 

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This site was created by Michelle Meche and is maintained by David Wm. Reed. Any comments or suggestions should be e-mailed to D.W. Reed at e-mail: dwreed@tamu.edu. If you use
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