pinnae
Quick Summary
In plant anatomy, a pinna (plural: pinnae) is a leaflet or primary division of a pinnate leaf or frond. Fern leaves, also called fronds, are typically pinnate, meaning they are featherlike with a central axis and smaller side branches. The pinnae themselves can be further divided into smaller segments called pinnules. This structure allows for a wide diversity of leaf shapes to evolve within different fern species. The term "pinna" can also refer to other projecting body parts, such as feathers, wings, or fins, and specifically to the external part of the ear.123
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