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angiosperm: Leaves
The basic angiosperm leaf is created of a leaf base, two stipules, a petiole, and also a blade (lamina). The...

Leaf morphology

Typically, a leaf is composed of a broad expanded tongue (the lamina), attached come the plant stem through a stalklike petiole. In angiosperms leaves generally have a pair that structures recognized as stipules, i m sorry are situated on every side of the sheet base and also may resemble scales, spines, glands, or leaflike structures. Leaves are, however, quite diverse in size, shape, and various various other characteristics, consisting of the nature that the tongue margin and also the kind of venation (arrangement the veins). Once only a solitary blade is inserted directly on the petiole, the leaf is calledsimple. The spare of straightforward leaves might be entire and smooth or they may be lobed in various ways. The coarse teeth of dentate margins project at best angles, while those of serrate margins point toward the leaf apex. Crenulate margins have rounded teeth or scalloped margins. Sheet margins of basic leaves might be lobed in among two patterns, pinnate or palmate. In pinnately lobed spare the leaf blade (lamina) is indented same deep follow me each next of the midrib (as in thewhite oak,Quercus alba), and in palmately lobed spare part the lamina is indented along several significant veins (as in thered maple,Acer rubrum). A an excellent variety the base and also apex shapes likewise are found. The sheet may additionally be decreased to a spine or scale.


Pain bush, or afri poison ivy (Smodingium argutum). The varieties is poisonous due to the fact that of the sap the emits.

Veins, which assistance the lamina and transport materials to and from the sheet tissues, radiate through the lamina native the petiole. The varieties of venation are characteristic of various kinds of plants: for example, dicotyledons such as poplars and lettuce have actually netlike venation and usually totally free vein endings; monocotyledons like lilies and bamboo have parallel venation and rarely free vein endings.

leaf: veins
Close-up that veins in a leaf.

Leaf modifications

Whole leaves or components of pipeline are regularly modified for unique functions, such as for climbing and also substrate attachment, storage, protection versus predation or climatic conditions, or trapping and digestinginsectprey. In temperate trees pipeline are simply protectivebudscales; in the spring when shoot development is resumed, they regularly exhibit a finish growth series from bud scale to totally developed leaves.

Spinesare additionally modified leaves. Incacti, spines space wholly transformed leaves that protect theplantfrom herbivores, radiate heat from thestemduring the day, and collect and drip condensed water vapour during the cooler night. In the manyspeciesof the spurge household (Euphorbiaceae), the stipules room modified right into paired stipular spines and also the blade creates fully. Inocotillo(Fouquieria splendens), the blade falls off and the petiole stays as a spine.

fishhook cactus
Fishhook cactus (Mammillaria).
Gary M. Stolz/U.S. Fish and Wildlife Service

Many desert plants, such together Lithops andaloe, construct succulent leaves for water storage. The many common type of storage leaves are the succulent sheet bases the undergroundbulbs(e.g.,tulipandCrocus) that offer as either water- or food-storage offal or both. Plenty of nonparasitic tree that flourish on the surface of various other plants (epiphytes), such as few of thebromeliads, absorb water through devoted hairs on the surface of your leaves. In thewater hyacinth(Eichhornia crassipes), swollen petioles keep the tree afloat.

Gelatinous inner of the pipeline of aloe (Aloe vera), a succulent plant.

Leaves or sheet parts might be modification to carry out support.Tendrilsand hooks room the most typical of these modifications. In the flamelily(Gloriosa superba), the leaf reminder of the tongue elongates right into a tendril and also twines approximately other plants because that support. In thegarden pea(Pisum sativum), the terminal leaflet the thecompoundleaf develops as a tendril. Innasturtium(Tropaeolum majus) andClematis, the petioles coil around other plants for support. In catbrier (Smilax), the stipules duty as tendrils. Numerous monocotyledons have sheathing sheet bases that space concentrically i ordered it and form a pseudotrunk, together inbanana(Musa). In plenty of epiphytic bromeliads, the pseudotrunk also functions as a water reservoir.

Tendrils that catbrier (Smilax rotundifolia). The stipules elongate and also coil roughly other plants for support.

Carnivorous plantsuse their very modified leaves to attract and trapinsects. Glands in the pipeline secrete enzymes the digest the caught insects, and also the leaves then absorb the nitrogenouscompounds(amino acids) and also other products of digestion. Plants that usage insects as a nitrogen source tend to thrive in nitrogen-deficient soils.

slender pitcher plant
Pitcher-shaped leaves of the carnivorous slim pitcher tree (Nepenthes gracilis).

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Leaves are essentially short-lived structures. Even when castle persist for two or three years, as in coniferous and also broad-leaved evergreens, lock make tiny contribution come the tree after the very first year. The fall of leaves, whether in the an initial autumn in most deciduous trees or after numerous years in evergreens, outcomes from the development of a weak zone, the abscission layer, at the basic of the petiole. Abscission layers may also type when leaves are seriously damaged by insects, disease, or drought. Together a result, a zone the cells throughout the petiole i do not care softened until the leaf falls. A healing layer then develops on the stem and also closes the wound, leave the sheet scar, a prominent function in many winter twigs and also an help in identification.