Site focus
   Navigating the site
   Why ferns are hard to identify
   Illustrated Glossary
   Flora of Australia
   Lower Vascular Plant Glossary
Hardy Fern Glossary
   Structure and Shape
   Blade Division
   Hairs and Scales
   Sori and Indusia
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: Fern Structure

The parts of the fern are a required vocabulary for making effective use of this site.

Fern Axes IllustratedAt left are two fronds, one 3 times divided, the other simple. This site assumes knowledge of most of the terms illustrated; learning them all is encouraged. In particular, one must, must, must know:
stipe the stem of the leaf or frond; sometimes called the petiole;
blade the leaf or frond above the stipe or stem
lamina the surface of the blade
midrib the main axis of a part of the blade; in a simple frond, the rachis
rachis the main axis of the blade; the midrib of the blade
pinna the first division of the blade
costa the midrib of the pinna
pinnule the first division of the pinna
costule the midrib of the pinnule
segment the smallest division of a frond, explicit definition varies depending on the degree of division, here a pinnulet

Shapes and Forms

A few shapes occur again and again. Some apply strictly to the lamina, some to scales or to vascular bundles. The most commonly encountered ones are:

deltate elliptic lanceolate linear ovate lunate
deltate form elliptic form lanceolate form linear form ovate form lunate form

Here is a broader set of forms, most infrequently used on this site.

Complete Lamina Forms
84 reniform88 trapeziform60 deltate80 ovate
73 lunulate63 falcate64 flabellate69 lanceolate
72 lunate87 subulate71 linear62 elliptic
79 orbiculate86 spathulate77 oblong85 rhombiform
61 dimidate57 acicular68 lanceate89 triangular
All the illustrations here are from A Modern Multilingual Glossary for Taxonomic Pteridology , David B. Lellinger, American Fern Society, 2002, with permission.
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