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Chart illustrating leaf morphology terms. The following terms are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple (that is, the leaf blade or 'lamina' is undivided) or compound (that is, the leaf blade is divided into two or more leaflets). [1]
A hastula is a flap of tissue borne at the insertion of the blade on the petiole on the upper, lower, or both leaf surfaces [8] [9] Bifurcate fronds may also develop. The extinct Devonian seed plant Cosmosperma polyloba demonstrated the early evolutionary diversification of frond branching patterns, presenting both bifurcate and trifurcate types.
A leaf (pl.: leaves) is a principal appendage of the stem of a vascular plant, [1] usually borne laterally above ground and specialized for photosynthesis.Leaves are collectively called foliage, as in "autumn foliage", [2] [3] while the leaves, stem, flower, and fruit collectively form the shoot system. [4]
(of a compound leaf) Having precisely two leaflet s, usually in a symmetrical pair, e.g. a leaf of Colophospermum mopane. Compare jugate lobed leaf, e.g. most species of Bauhinia. bifusiform Fusiform with a pinch in the middle. bilabiate Having two lips, e.g. the form of the petal s in many irregular flowers. bilateral 1.
Leaf of Pyrus calleryana with petiole. In botany, the petiole (/ ˈ p iː t i. oʊ l /) is the stalk that attaches the leaf blade to the stem. [1]: 87 [2]: 171 It is able to twist the leaf to face the sun, producing a characteristic foliage arrangement (spacing of blades), and also optimizing its exposure to sunlight.
Leaflet – a separate blade, among others, of a compound leaf; Ligule – a projection from the top of the sheath on the adaxial side of the sheath-blade joint in grasses. Midrib – the central vein of the leaf blade. Midvein – the central vein of a leaflet. Petiole – a leaf stalk supporting a blade and attaching to a stem at a node.
The ligule is part of the leaf that is found at the junction of the blade and sheath of the leaf. It may take several forms, but it is commonly some form of translucent membrane or a fringe of hairs. The membranous ligule can be very short 1–2 mm ( Kentucky bluegrass , Poa pratensis ) to very long 10–20 mm ( Johnson grass , Sorghum ...
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.