Plant Identification Keys

A plant identification key can be a useful tool for identifying plants. I am most familiar with a single-access, or dichotomous key, which focuses on physical characteristics  such as leaves or flowers, and provides a series of decision points for eliminating plant categories, and proceeding to possible categories. The plant kingdom is large, so categorization helps.

This example from Wikipedia’s article on single-access keys uses eastern oaks as the category (see http://en.wikipedia.org/wiki/Dichotomous_key):

Sample dichotomous key. In 1, identify the general shape of the leaf.
Based on that decision, go to either 2 or 5.
Finally, you are referred to a possible tree name, such as 6. 

Other types of plant identification key include:

• Picture key. Several of my books for identifying desert flowers categorize flowers by color. To identify a blue flower, for example, you navigate to the blue section, and flip through the pictures to find matches, including Parish Larkspur, Smoke Tree, and Indigo Bush.
• Morphology key. Yet another type of plant identification key uses plant and flower morphology to identify plants. I haven’t worked with this approach yet, but as I learn more this may be a more accurate approach.
• Random access (or multi-access) key. For a mystery plant, a database search engine might be the best option, like this one from the Burke Museum of Natural History associated with the University of Washington Herbarium: http://biology.burke.washington.edu/herbarium/imagecollection.php?Page=plantkey.php. You supply as much information or knowledge as you can, and the program searches its database for possible matches.