Dichotomous Key

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:  

 

Pinto

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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