Pinnate
Pinnate is a term used to describe
feather-like or multi-divided features arising from both sides of a common axis in
plant or
animal structures, and comes from the
Latin word
pinna for "feather". A similar term is
pectinate, which refers to a
comb-like arrangement of parts (arising from one side of an axis). The term contrasts somewhat with
palmate, in which the parts or structures radiate out from a common point.
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A pinnate frond of the fern, Blechnum appendiculatum. |
Botanically, the term describes an arrangement of discrete structures (such as leaflets, veins, lobes, branches, or appendages) arising at multiple points along a common axis. For example, once-divided leaf blades having leaflets arranged on both sides of a
rachis are
pinnately compound leaves. Many
palms (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 ferns the leaflets are typically referred to as "pinnae" (singular "pinna"). Plants with pinnate leaves are sometimes colloquially called "feather-leaved".
pinnatifid – leaves with pinnate lobes that are not discrete, remaining sufficiently connected to each other that they are not separate leaflets.
paripinnate – pinnately-compound leaves in which leaflets are born in pairs along the rachis without a single terminal leaflet; also called "even-pinnate".
imparipinnate – pinnately-compound leaves in which there is a lone terminal leaflet rather than a terminal pair of leaflets; also called "odd-pinnate".
bipinnate – pinnately-compound leaves in which the leaflets are themselves pinnately-compound; also called "twice-pinnate".
tripinnate – pinnately-compound leaves in which the leaflets are themselves bipinnate; also called "thrice-pinnate".
tetrapinnate – pinnately-compound leaves in which the leaflets are themselves tripinnate.
The fish,
Platax pinnatus, is known as the
pinnate spadefish or
pinnate batfish.
