Glossary: Division of the Lamina

Here on Hardy Fern Library frond shapes are classified using a somewhat simplified nomenclature. (Click the images to bring up the original pages.)

Special Cases	simple	forking	palmate
Least Division	pinnatifid	1-pinnate	1-pinnate-pinnatifid
Moderate Division		2-pinnate	2-pinnate-pinnatifid
Greatest Division		3-pinnate	3-pinnate-pinnatifid

These examples were chosen for their relative lack of ambiguity. The real world is frequently more complex. Most ferns, and nearly unanimously with the more divided species, tend to diminish in degree of division above the base, degenerating to a pinnatifid apex. So, in determining division, start with the base of the blade. If the lowest pair uniquely exhibit the highest degree of division, the description ought to note that, e.g., 3-pinnate at the base. Still, there will be ambiguous cases as when only one segment of one pinnule of one pinna passes over the line from lobed to pinnatifid; in such cases your search for a match will have to include two possibilities. Two is still a lot less than ten.

However, when you leave this site and explore floras or other texts, the terminology often becomes more specific. In general, disagreements on the meanings of pteridophyte terms necessitate refering to the glossaries always included in your text of interest. Here is one detailed, authoritative breakdown:

174 simple 165 lobate	170 pinnatifid 166 pectinate	171 pinnatisect 167 pinnate	159 bipinnate 162 bipinnatifid
From A Modern Multilingual Glossary for Taxonomic Pteridology , David B. Lellinger, American Fern Society, 2002, with permission.