Dichotomous Key
The identification of biological organisms can be greatly simplified using tools such as dichotomous keys. A dichotomous key is an organized set of couplets of mutually exclusive characteristics of biological organisms. You simply compare the characteristics of an unknown organism against an appropriate dichotomous key. These keys will begin with general characteristics and lead to couplets indicating progressively specific characteristics. If the organism falls into one category, you go to the next indicated couplet. By following the key and making the correct choices, you should be able to identify your specimen to the indicated taxonomic level.
Sample key to some common beans used in the kitchen:
 |  |  |  |  |
| 1a. | Bean round | Garbanzo bean |
| 1b. | Bean elliptical or oblong | Go to 2 |
| 2a. | Bean white | White northern |
| 2b. | Bean has dark pigments | Go to 3 |
| 3a. | Bean evenly pigmented | Go to 4 |
| 3b. | Bean pigmentation mottled | Pinto bean |
| 4a. | Bean black | Black bean |
| 4b. | Bean reddish-brown | Kidney bean |
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