Key to Vesiculate Grains
Key to Tetrad and Polyad Grains
Key to Bilaterally Symmetrical Grains and Spores
Key to Inaperturate and Irregular Grains
Key to Subtetrahedral Spores
Submaster Key to Rotational Grains
Note: It can be difficult to decide, from some single grains, if it is porate, colpate, or colporate, particularly if you can’t rotate the grain. Frequently, but not always, colporate grains will have costa endocolpi, meridionally oriented internal ridges that follow the lines of the furrows. These grains will have breaks in the costa endocolpi at the location of the pore that can be seen when focusing down through the grain. Some taxa included in this key are exceedingly difficult to categorize as colpate or colporate from observation of slides containing multiple grains. In these cases assignment to a section of the key was based on the standard interpretation of Erdtman. Users of the key may find it necessary to run a few unknown pollens through the appropriate subsection of the colpate and colporate keys for an identification.
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