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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.
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.
The leaves of the tropical genera are usually spirally alternate, while those of the temperate maples , Aesculus, and a few other genera are opposite. They are most often pinnately compound, [3] but are palmately compound in Aesculus, and simply palmate in Acer. The petiole has a swollen base and lacks stipules. [4]
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]
As described above, Aralia nudicaulis has pinnately compound leaves while Panax quinquefolius has palmately compound leaves (with leaflets radiating from a single point). [ 6 ] Because it sometimes grows with groups of 3 leaflets, it can be mistaken for poison ivy ; the way to tell the difference is that Wild Sarsaparilla lacks a woody base and ...