Glossary: Fern Structure
The parts of the fern are a required vocabulary for making effective use of this site.
Axes At 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:
Here is a broader set of forms, most infrequently used on this site.
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