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Compound leaves may be pinnate with pinnae (leaflets) on both sides of a rachis (axis), or may be palmate with multiple leaflets arising from a single point. [1] Leaf structure is described by several terms that include: Bipinnate leaf anatomy with labels showing alternative usages A ternate compound leaf with a petiole but no rachis (or rachillae)
The two main classes of compound leaf morphology are palmate and pinnate. For example, a hemp plant has palmate compound leaves, whereas some species of Acacia have pinnate leaves. The ultimate free division (or leaflet) of a compound leaf, or a pinnate subdivision of a multipinnate leaf is called a pinnule or pinnula.
Composed of several parts, e.g. a leaf composed of multiple leaflet s, a gynoecium composed of multiple carpel s, or an inflorescence made up of multiple smaller inflorescences. compound palmate Having leaflet s that radiate from a central point (usually at the top of a petiole), like spread-out fingers radiating from the palm of a hand ...
paripinnate: pinnately compound leaves in which leaflets are borne 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".
The middle vein of a compound leaf or a frond, when it is present, is called a rachis. Palmately compound The leaflets all have a common point of attachment at the end of the petiole, radiating like fingers of a hand; for example, Cannabis (hemp) and Aesculus (buckeyes). Pinnately compound Leaflets are arranged either side of the main axis, or ...
Some fronds are not pinnately compound (or simple), but may be palmate, costapalmate, or bifurcate. There is a spectrum from costapalmate to palmate. Costapalmate fronds are shaped like the palm of a hand and have a short midrib or costa. Palmate fronds are also shaped like the palm of the hand, but all ribs or leaflets arise from a central area.
Palms have large, evergreen leaves that are either palmately ('fan-leaved') or pinnately ('feather-leaved') compound and spirally arranged at the top of the stem. The leaves have a tubular sheath at the base that usually splits open on one side at maturity. [9]
Petiole – a leaf stalk supporting a blade and attaching to a stem at a node. Petiolule - the leaf stalk of a leaflet. Pulvinus – the swollen base of a petiole or petiolule, usually involved in leaf movements and leaf orientation. Rachilla – a secondary axis of a multiply compound leaf. Rachis – main axis of a pinnately compound leaf.