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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)
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".
Doubly pinnate; e.g. a compound leaf with individual leaflet s pinnately divided. bipinnatisect A pinnatisect leaf with deeply dissected segments. bisexual Bearing both male and female reproductive organs; usually, flowers with both stamen s and carpel s; synonymous with hermaphrodite, synoecious, and monoclinous.
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.
Vein – the externally visible vascular bundles found on leaves, petals, and other parts. Veinlet – a small vein. Leaf Arrangement or Phyllotaxy: Whorl – three or more leaves or branches or pedicels arising from the same node. Leaf Type: Abruptly pinnate – a compound leaf without a terminal leaflet. Leaf Blade Shape:
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 ...
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]
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.