In botany, the petiole ( // ) is the stalk that attaches the leaf blade to the stem, :87 :171 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 stipules. Leaves with a petiole are said to be petiolate, while leaves lacking a petiole are called sessile or apetiolate.[ citation needed ]
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. 157 The broomrape family Orobanchaceae is an example of a family in which the leaves are always sessile. :639 In some other plant groups, such as the speedwell genus Veronica , petiolate and sessile leaves may occur in different species. :584:
In the grasses (Poaceae), 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 . 391:
In plants with compound leaves, the leaflets are attached to a continuation of the petiole called the rachis. 98 Each leaflet may be attached to the rachis by a short stalk called the petiolule. :87 There may be swollen regions at either end of the petiole known as pulvina (singular=pulvinus) :97 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. 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 , especially the Australian species, at one time put in Acacia subgenus Phyllodineae.
In Acacia koa , 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 ), celery ( Apium graveolens ), artichokes, and cardoons (Cynara cardunculus), the petioles ("stalks" or "ribs") are cultivated as edible crops. The petiole of rhubarb grows directly from the rhizome and produces the leaf at its end. Botanically it is categorized as a vegetable and culinarily used as a fruit.
Petiole comes from Latin petiolus, or peciolus "little foot", "stem", an alternative diminutive of pes "foot". The regular diminutive pediculus is also used for "foot stalk".
Rhubarb is the fleshy, edible stalks (petioles) of species and hybrids of Rheum in the family Polygonaceae, which are cooked and used for food. The whole plant – a herbaceous perennial growing from short, thick rhizomes – is also called rhubarb. Historically, different plants have been called "rhubarb" in English. The large, triangular leaves contain high levels of oxalic acid and anthrone glycosides, making them inedible. The small flowers are grouped in large compound leafy greenish-white to rose-red inflorescences.
A frond is a large, divided leaf. In both common usage and botanical nomenclature, the leaves of ferns are referred to as fronds and some botanists restrict the term to this group. Other botanists allow the term frond to also apply to the large leaves of cycads, as well as palms (Arecaceae) and various other flowering plants, such as mimosa or sumac. "Frond" is commonly used to identify a large, compound leaf, but if the term is used botanically to refer to the leaves of ferns and algae it may be applied to smaller and undivided leaves.
Celeriac, also called celery root, knob celery, and turnip-rooted celery, is a variety of celery cultivated for its edible stem or hypocotyl, and shoots. Celeriac is like a root vegetable except it has a bulbous hypocotyl with many small roots attached.
The following is a list of terms which are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple or compound. The edge of the leaf may be regular or irregular, may be smooth or bearing hair, bristles or spines. For more terms describing other aspects of leaves besides their overall morphology see the leaf article.
Phyllodes are modified petioles or leaf stems, which are leaf-like in appearance and function. In some plants, these become flattened and widened, while the leaf itself becomes reduced or vanishes altogether. Thus the phyllode comes to serve the purpose of the leaf. Some important examples are Euphorbia royleana which are cylindrical and Opuntia which are flattened.
Anemonoides quinquefolia, a flowering plant in the buttercup family Ranunculaceae, is native to North America. It is commonly called wood anemone or windflower, not to be confused with Anemonoides nemorosa, a closely related European species also known by these common names. The specific epithet quinquefolia means "five-leaved", which is a misnomer since each leaf has just three leaflets. A plant typically has a single, small white flower with 5 sepals.
Thalictrum thalictroides, synonym Anemonella thalictroides, the rue-anemone, is a herbaceous perennial plant native to woodland in eastern North America. It has white or pink flowers surrounded by a whorl of leaflets, and it blooms in spring.
Ceratozamia is a genus of New World cycads in the family Zamiaceae. The genus contains 27 known currently living species and one or two fossil species. Most species are endemic to mountainous areas of Mexico, while few species extend into the mountains of Guatemala, Honduras and Belize. The genus name comes from the Greek ceras, meaning horn, which refers to the paired, spreading horny projections on the male and female sporophylls of all species.
Attalea crassispatha is a palm which is endemic to southwest Haiti. The most geographically isolated member of the genus, it is considered a critically endangered species and has been called one of the rarest palms in the Americas.
This page provides a glossary of plant morphology. Botanists and other biologists who study plant morphology use a number of different terms to classify and identify plant organs and parts that can be observed using no more than a handheld magnifying lens. This page provides help in understanding the numerous other pages describing plants by their various taxa. The accompanying page—Plant morphology—provides an overview of the science of the external form of plants. There is also an alphabetical list: Glossary of botanical terms. In contrast, this page deals with botanical terms in a systematic manner, with some illustrations, and organized by plant anatomy and function in plant physiology.
A pulvinus 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 family Marantaceae.
Korthalsia is a clustering genus of flowering plant in the palm family spread throughout Southeast Asia. It is a highly specialized rattan with some species known to have an intimate relationship with ants, hence the common name ant rattan. High-climbing and armed with spines, the genus is named for the Dutch botanist P. W. Korthals who first collected them from Indonesia.
Myrialepis is a monotypic genus of flowering plant in the palm family, the single species, Myrialepis paradoxa, native to Southeast Asia. The genus name is a combination of the Greek words meaning "innumerable" and "scale", a description of the fruit, and the epithet is Latin for "paradox".
This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary of leaf morphology. For other related terms, see Glossary of phytopathology and List of Latin and Greek words commonly used in systematic names.
A leaf is the principal lateral appendage of the vascular plant stem, usually borne above ground and specialized for photosynthesis. The leaves, stem, flower and fruit together form the shoot system. Leaves are collectively referred to as foliage, as in "autumn foliage". In most leaves, the primary photosynthetic tissue, the palisade mesophyll, is located on the upper side of the blade or lamina of the leaf but in some species, including the mature foliage of Eucalyptus, palisade mesophyll is present on both sides and the leaves are said to be isobilateral. Most leaves are flattened and have distinct upper and lower surfaces that differ in color, hairiness, the number of stomata, the amount and structure of epicuticular wax and other features. Leaves are mostly green in color due to the presence of a compound called chlorophyll that is essential for photosynthesis as it absorbs light energy from the sun. A leaf with lighter-colored or white patches or edges is called a variegated leaf.
Lepidobotryaceae is a flowering plant family in the order Celastrales. It contains only two genera, each with a single species: Lepidobotrys staudtii and Ruptiliocarpon caracolito.
Acacia burkittii is a species of wattle endemic to Western Australia, South Australia and western New South Wales, where it is found in arid zones, and is a perennial shrub in the family Fabaceae. Common names for it include Burkitt's wattle, fine leaf jam, gunderbluey, pin bush and sandhill wattle. It has also been introduced into India. Previously this species was referred to as Acacia acuminata subsp. burkittii, but is now considered to be a separate species. Grows in mallee, eucalypt and mulga woodland or shrubland, often on sandhills.
Licuala cattienensis, is a small fan palm, endemic to southern Vietnam. The type locality is in Cát Tiên National Park in Đồng Nai Province, growing in seasonal tropical forest in flat areas near rivers at low elevations. It is recognisable by being much smaller (<2m) and single-stemmed, in comparison the larger L. spinosa, which is common in the Park and grows in grows in clumps.
Rhus boothillensis is an extinct species of flowering plant in the sumac family Anacardiaceae. The species is known from fossil leaves found in the early Eocene deposits of northern Washington State, United States. The species was first described from fossil leaves found in the Klondike Mountain Formation. Rhus boothillensis likely hybridized with the other Klondike Mountain formation sumac species Rhus garwellii, Rhus malloryi, and Rhus republicensis.
Otholobium lanceolatum is a small subshrub of up to 20 cm (7.9 in) high, that is assigned to the Pea family. It has up to 7 horizontal stems with raised tips, few hairless, alternately set leaves with only one leaflet and clusters of 15-27 white, pea-like flowers with a purple tip near the top of the short, seasonal shoots. It is endemic to one site near Caledon, South Africa. Flowers only appear in November and December within one year after a fire destroyed the vegetation.
|Wikimedia Commons has media related to petioles .|