botany Botany, also called , plant biology or phytology, is the science of plant life and a branch of biology. A botanist, plant scientist or phytologist is a scientist who specialises in this field. The term "botany" comes from the Ancient Greek w ...

, the petiole () is the stalk that attaches the

leaf A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, ste ...

blade to the stem, and is able to twist the leaf to face the sun. This gives a characteristic foliage arrangement to the plant. Outgrowths appearing on each side of the petiole in some species are called

stipule In botany, a stipule is an outgrowth typically borne on both sides (sometimes on just one side) of the base of a leafstalk (the petiole). Stipules are considered part of the anatomy of the leaf of a typical flowering plant, although in many speci ...

s. Leaves with a petiole are said to be petiolate, while leaves lacking a petiole are called

sessile Sessility, or sessile, may refer to: * Sessility (motility), organisms which are not able to move about * Sessility (botany), flowers or leaves that grow directly from the stem or peduncle of a plant * Sessility (medicine), tumors and polyps that ...

or apetiolate.

Description

The petiole is a stalk that attaches a leaf to the plant stem. In petiolate leaves, the leaf stalk may be long, as in the leaves of celery and rhubarb, or short. When completely absent, the blade attaches directly to the stem and is said to be sessile. Subpetiolate leaves have an extremely short petiole, and may appear sessile. The broomrape family

Orobanchaceae Orobanchaceae, the broomrapes, is a family of mostly parasitic plants of the order Lamiales, with about 90 genera and more than 2000 species. Many of these genera (e.g., ''Pedicularis'', ''Rhinanthus'', ''Striga'') were formerly included in th ...

is an example of a family in which the leaves are always sessile. In some other plant groups, such as the speedwell genus '' Veronica'', petiolate and sessile leaves may occur in different species. In the grasses (

Poaceae Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns an ...

), the leaves are apetiolate, but the leaf blade may be narrowed at the junction with the leaf sheath to form a ''pseudopetiole'', as in ''

Pseudosasa japonica ''Pseudosasa japonica'', the arrow bamboo or ''metake'', is a species of flowering plant in the grass family Poaceae, native to Japan and Korea. This vigorous bamboo forms thickets up to tall with shiny leaves up to long. The culms are typical ...

''. In plants with

compound leaves A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, ste ...

, the leaflets are attached to a continuation of the petiole called the

rachis In biology, a rachis (from the grc, ῥάχις [], "backbone, spine") is a main axis or "shaft". In zoology and microbiology In vertebrates, ''rachis'' can refer to the series of articulated vertebrae, which encase the spinal cord. In this c ...

. Each leaflet may be attached to the rachis by a short stalk called the petiolule. There may be swollen regions at either end of the petiole known as pulvina (singular =

pulvinus A pulvinus (pl. ''pulvini'') is a joint-like thickening at the base of a plant leaf or leaflet that facilitates growth-independent movement. Pulvini are common, for example, in members of the bean family Fabaceae (Leguminosae) and the prayer plant ...

) that are composed of a flexible tissue that allows leaf movement. Pulvina are common in the bean family Fabaceae and the prayer plant family

Marantaceae The Marantaceae are a family, the arrowroot family, of flowering plants consisting of 31 genera and around 530 species, defining it as one of the most species-rich families in its order.Kennedy, H. (2000). “Diversification in pollination mechan ...

. A pulvinus on a petiolule is called a pulvinulus. In some plants, the petioles are flattened and widened to become phyllodes (also known as phyllodia or cladophylls) and the true leaves may be reduced or absent. Thus, the phyllode comes to serve the functions of the leaf. Phyllodes are common in the genus ''

Acacia ''Acacia'', commonly known as the wattles or acacias, is a large genus of shrubs and trees in the subfamily Mimosoideae of the pea family Fabaceae. Initially, it comprised a group of plant species native to Africa and Australasia. The genus na ...

'', especially the Australian species, at one time put in ''Acacia'' subgenus ''Phyllodineae''. In ''

Acacia koa ''Acacia koa'' or commonly known as koa is a species of flowering tree in the family Fabaceae. It is endemic to the Hawaiian Islands, where it is the second most common tree. The highest populations are on Hawaii, Maui and Oahu. Name The name ...

'', the phyllodes are leathery and thick, allowing the tree to survive stressful environments. The petiole allows partially submerged

hydrophyte Aquatic plants are plants that have adapted to living in aquatic environments (saltwater or freshwater). They are also referred to as hydrophytes or macrophytes to distinguish them from algae and other microphytes. A macrophyte is a plant that g ...

s to have leaves floating at different depths, the petiole being between the node and the stem. In plants such as rhubarb (''

Rheum rhabarbarum ''Rheum rhabarbarum'' is a species of flowering plant in the family Polygonaceae, native to a region stretching from southern Siberia to north and central China. It has been harvested from the wild for centuries for its root, which was harvested ...

''), celery (''

Apium graveolens Celery (''Apium graveolens'') is a marshland plant in the family Apiaceae that has been cultivated as a vegetable since antiquity. Celery has a long fibrous stalk tapering into leaves. Depending on location and cultivar, either its stalks, lea ...

''),

artichokes The globe artichoke (''Cynara cardunculus'' var. ''scolymus'' ),Rottenberg, A., and D. Zohary, 1996: "The wild ancestry of the cultivated artichoke." Genet. Res. Crop Evol. 43, 53–58. also known by the names French artichoke and green articho ...

, and

cardoons The cardoon, ''Cynara cardunculus'' (), also called the artichoke thistle, is a thistle in the family Asteraceae. It is a naturally occurring species that also has many cultivated forms, including the globe artichoke. It is native to the wester ...

(''Cynara cardunculus''), the petioles ("stalks" or "ribs") are cultivated as edible crops. The petiole of rhubarb grows directly from the

rhizome In botany and dendrology, a rhizome (; , ) is a modified subterranean plant stem that sends out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow hori ...

and produces the leaf at its end. Botanically, it is categorized as a vegetable but, culinarily, it is more often used as a fruit.

Etymology

''Petiole'' comes from

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

'' petiolus'', or ''peciolus'' "little foot", "stem", an alternative

diminutive A diminutive is a root word that has been modified to convey a slighter degree of its root meaning, either to convey the smallness of the object or quality named, or to convey a sense of intimacy or endearment. A (abbreviated ) is a word-formati ...

of ''pes'' "foot". The regular diminutive ''pediculus'' is also used for "foot stalk".

References

External links

* {{DEFAULTSORT:Petiole (Botany) Plant morphology de:Blatt (Pflanze)#Blattstiel he:פטוטרת fi:Lehtiruoti

Description

Etymology

See also

References

External links