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Major Fern Links

    Adiantum  Arachniodes
    Aspidotis  Asplenium
    Astrolepis  Athyrium
    Blechnum  Cheilanthes
    Cryptogramma  Cyrtomium
    Cystopteris  Dennstaedtia
    Deparia  Diplazium
    Dryopteris  Gymnocarpium
    Lygodium  Matteuccia
    Onoclea  Oreopteris
    Osmunda  Pellaea
    Phegopteris  Pleopeltis
    Polypodium  Polystichum
    Pteridium  Pteris
    Pyrrosia  Thelypteris
    Woodsia  Woodwardia

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 fronds
forking fronds
palmate frond
Least Division pinnatifid frond
1-pinnate frond
1-pinnate-pinnatifid frond
Moderate Division 2-pinnate frond
2-pinnate-pinnatifid frond
Greatest Division  frond (part)
3-pinnate-pinnatifid frond

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:

Division of the Lamina
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.
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