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[citation needed] Leaves may be simple, with a single leaf blade, or compound, with several leaflets. 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:
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 primary leaf or leaves of a plant embryo which upon germination develops into the seed-leaf or the first set of leaves. craspedodromous Pinnate venation in which the secondary veins terminate at the margin s, often as teeth. crateriform In the shape of a saucer or shallow cup; hemispherical or more shallow. cremnophyte
The leaves are pinnate (in the form of bird feathers, pinnae), with a central leaf stalk from which parallel "ribs" emerge from each side of the stalk, perpendicular to it. The leaves are typically either compound (with leaflets emerging from the leaf stalk as "ribs"), or have edges ( margins ) so deeply cut ( incised ) so as to appear compound.
The blades may be simple (undivided), pinnatifid (deeply incised, but not truly compound), pinnate (compound with the leaflets arranged along a rachis to resemble a feather), or further compound (subdivided). If compound, a frond may be compound once, twice, or more.
A pinnate leaf with just three leaflets; for example, Trifolium (clover), Laburnum (laburnum), and some species of Toxicodendron (for instance, poison ivy). Pinnatifid Pinnately dissected to the central vein, but with the leaflets not entirely separate; for example, Polypodium, some Sorbus (whitebeams).
The leaves are alternate and are a shiny dark green on top and light brown on the bottom. They are simple leaf types with pinnate venation. The leaves are ovate and range in length from 3 to 11 cm (1.2 to 4.3 in). The breadth of the leaves ranges from 2 to 5 cm (0.79 to 1.97 in). The leaves are evergreen so they are present year round.
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.