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In
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 wo ...

botany
, the petiole () is the stalk that attaches the
leaf A leaf (plural leaves) is the principal lateral appendage of the , usually borne above ground and specialized for . The leaves, stem, flower and fruit together form the system. Leaves are collectively referred to as foliage, as in "autu ...

leaf
blade to the
stem Stem or STEM may refer to: Biology * Plant stem '' has lost its leaves, but is producing adventitious roots from the nodes. A stem is one of two main structural axes of a vascular plant, the other being the root In vascular plants, the roo ...

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
stipuleIn 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 ...
s. Leaves with a petiole are said to be petiolate, while leaves lacking a petiole are called sessile or apetiolate. For the use of the term in entomology see
petiole (insect anatomy) In entomology, petiole is the technical term for the narrow waist of some hymenopteran insects, especially ants, bees, and wasps in the suborder Apocrita. The petiole can consist of either one or two segments, a characteristic that separate ...


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, short or completely absent, in which case 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 In human society A society is a Social group, group of individuals involved in persistent Social relation, social interaction, or a large social group sharing the same spatial or social terr ...
is an example of a family in which the leaves are always sessile. In some other plant groups, such as the speedwell genus ''
VeronicaVeronica, Veronika, etc., may refer to: People * Veronica (name) Veronica (also spelled Weronika, Veronika, Verónica or Verônica) is a female given name, the Latin transliteration of the Greek language, Greek name Berenice, Βερενίκη, wh ...

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 known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawn law ...
), the leaves are apetiolate, but the leaf blade may be narrowed at the junction with the leaf sheath to form a ''pseudopetiole'', as in ''''. In plants with
compound leaves A leaf (plural leaves) is the principal lateral appendage of the vascular plant stem, usually borne above ground and specialized for photosynthesis Photosynthesis is a process used by plants and other organisms to convert light en ...
, the leaflets are attached to a continuation of the petiole called the
rachis feather In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological me ...
. 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 200px, Section through the pulvinus of '' Oxalis rosea'', from: Charles Darwin (1880): ''The Power of Movement in Plants">Charles_Darwin.html" ;"title="Oxalis rosea'', from: Charles Darwin">Oxalis rosea'', from: Charles Darwin (1880): ''The Power of ...

pulvinus
) that are composed of a flexible tissue that allows leaf movement. Pulvina are common in the bean family
Fabaceae The Fabaceae or Leguminosae,International Code of Nomenc ...

Fabaceae
and the prayer plant family
Marantaceae The Marantaceae are a family (biology), 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 p ...
. A pulvinus on a petiolule is called a pulvinulus. In some plants, the petioles are flattened and widened to become phyllodes (aka 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 Genus /ˈdʒiː.nəs/ (plural genera /ˈdʒen.ər.ə/) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as V ...

Acacia
'', especially the Australian species, at one time put in ''Acacia'' subgenus ''Phyllodineae''. In ''
Acacia koa ''Acacia koa'' is a species of flowering A flower, sometimes known as a bloom or blossom, is the reproductive Reproduction (or procreation or breeding) is the biological process by which new individual organisms – "offspring" – ...
'', the phyllodes are leathery and thick, allowing the tree to survive stressful environments. The petiole allows partially submerged hydrophytes 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 In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactio ...
''), celery (''
Apium graveolens Celery (''Apium graveolens'') is a marshland plant in the family Apiaceae Apiaceae or Umbelliferae is a family of mostly aromatic flowering plants named after the type genus ''Apium'' and commonly known as the celery, carrot or parsley family, ...

Apium graveolens
''), , and cardoons (''Cynara cardunculus''), the petioles ("stalks" or "ribs") are cultivated as edible crops. The petiole of rhubarb grows directly from the
rhizome In 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 A ...

rhizome
and produces the leaf at its end. Botanically it is categorized as a vegetable and culinarily used as a fruit.High Altitude Rhubarb
/ref>


Etymology

''Petiole'' comes from
Latin Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communication Communication (from Latin ''communicare'', meaning "to share" or "to be in relation with") is "an appa ...

Latin
''petiolus'', or ''peciolus'' "little foot", "stem", an alternative
diminutive A diminutive is a root word A root (or root word) is the core of a word that is irreducible into more meaningful elements. In morphology, a root is a morphologically simple unit which can be left bare or to which a prefix A prefix is an affi ...
of ''pes'' "foot". The regular diminutive ''pediculus'' is also used for "foot stalk".


See also

*
Hyponastic response The hyponastic response is an upward bending of leaf, leaves or other plant parts, resulting from accelerated growth of the lower side of the petiole (botany), petiole in comparison to its upper part. This can be observed in many terrestrial plants ...

Hyponastic response
*
Pedicel Pedicle or pedicel may refer to: Human anatomy *Pedicle of vertebral arch, the segment between the transverse process and the vertebral body, and is often used as a radiographic marker and entry point in vertebroplasty and kyphoplasty procedures * ...


References


External links

* {{DEFAULTSORT:Petiole (Botany)
Plant morphology ''Plant morphology'' is the field in botany that studies the diversity in forms, with the naked eye or slight optical magnification. This is opposed to plant anatomy (see :Plant anatomy) that needs to cut into plants to be able to study its subject, ...
de:Blatt (Pflanze)#Blattstiel he:פטוטרת fi:Lehtiruoti