Pinnation
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Pinnation is the arrangement of feather-like or multi-divided features arising from both sides of a common axis. Pinnation occurs in biological morphology, in crystals, such as some forms of ice or me
A simple pinnate (unipinnate) frond of the fern Blechnum appendiculatum.
Bipinnate leaves of species of palm in the genus Caryota
Frond
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A frond is a large, divided leaf. In both common usage and botanical nomenclature, the leaves of ferns are referred to as fronds and some botanists restrict the term to this group. Other botanists all
Pinnation
…notably the feather palms) and most cycads and grevilleas have pinnately divided leaves. Most species of ferns have pinnate or more highly divided fronds, and in ferns, the leaflets or segments are typically referred to as "pinnae" (singular "pinna"). Plants with pinnate leaves are sometimes colloquially…
A fern (Dryopteris decipiens) with simple (lobed or pinnatifid) blades, the dissection of each blade not quite reaching to the rachis.
A growing fern frond unfurling.
Unfurling fiddlehead fern frond