Decurrent
Encyclopedia
Decurrent is a term used in botany
and mycology
to describe plant or fungal parts that extend downward.
In botany, the term is most often applied to leaf blades that partly wrap or have wings around the stem or petiole and extend down along the stem. A "decurrent branching habit" is a plant form common for shrub
s and most angiosperm trees, contrasted with the excurrent or "cone-shaped crown" common among many gymnosperm
s. The decurrent habit is characterized by having weak apical dominance
that eventually produces a rounded or spreading tree crown. Examples of trees with decurrent habit are most hardwood
trees: oak
, hickory
, maple
, etc.
In mycology, the term is most often applied to the hymenophore
of a basidiocarp
(such as the lamellae or "gills" of a mushroom or the "pores" of a bracket fungus
) when it is broadly attached to and extends down the stipe
.
Botany
Botany, plant science, or plant biology is a branch of biology that involves the scientific study of plant life. Traditionally, botany also included the study of fungi, algae and viruses...
and mycology
Mycology
Mycology is the branch of biology concerned with the study of fungi, including their genetic and biochemical properties, their taxonomy and their use to humans as a source for tinder, medicinals , food and entheogens, as well as their dangers, such as poisoning or...
to describe plant or fungal parts that extend downward.
In botany, the term is most often applied to leaf blades that partly wrap or have wings around the stem or petiole and extend down along the stem. A "decurrent branching habit" is a plant form common for shrub
Shrub
A shrub or bush is distinguished from a tree by its multiple stems and shorter height, usually under 5–6 m tall. A large number of plants may become either shrubs or trees, depending on the growing conditions they experience...
s and most angiosperm trees, contrasted with the excurrent or "cone-shaped crown" common among many gymnosperm
Gymnosperm
The gymnosperms are a group of seed-bearing plants that includes conifers, cycads, Ginkgo, and Gnetales. The term "gymnosperm" comes from the Greek word gymnospermos , meaning "naked seeds", after the unenclosed condition of their seeds...
s. The decurrent habit is characterized by having weak apical dominance
Apical dominance
In plant physiology, apical dominance is the phenomenon whereby the main central stem of the plant is dominant over other side stems; on a branch the main stem of the branch is further dominant over its own side branchlets....
that eventually produces a rounded or spreading tree crown. Examples of trees with decurrent habit are most hardwood
Hardwood
Hardwood is wood from angiosperm trees . It may also be used for those trees themselves: these are usually broad-leaved; in temperate and boreal latitudes they are mostly deciduous, but in tropics and subtropics mostly evergreen.Hardwood contrasts with softwood...
trees: oak
Oak
An oak is a tree or shrub in the genus Quercus , of which about 600 species exist. "Oak" may also appear in the names of species in related genera, notably Lithocarpus...
, hickory
Hickory
Trees in the genus Carya are commonly known as hickory, derived from the Powhatan language of Virginia. The genus includes 17–19 species of deciduous trees with pinnately compound leaves and big nuts...
, maple
Maple
Acer is a genus of trees or shrubs commonly known as maple.Maples are variously classified in a family of their own, the Aceraceae, or together with the Hippocastanaceae included in the family Sapindaceae. Modern classifications, including the Angiosperm Phylogeny Group system, favour inclusion in...
, etc.
In mycology, the term is most often applied to the hymenophore
Hymenophore
A hymenophore refers to the hymenium-bearing structure of a fungal fruiting body. Hymenophores can be smooth surfaces, lamellae, folds, tubes, or teeth....
of a basidiocarp
Basidiocarp
In fungi, a basidiocarp, basidiome or basidioma , is the sporocarp of a basidiomycete, the multicellular structure on which the spore-producing hymenium is borne. Basidiocarps are characteristic of the hymenomycetes; rusts and smuts do not produce such structures...
(such as the lamellae or "gills" of a mushroom or the "pores" of a bracket fungus
Bracket fungus
Bracket fungi, or shelf fungi, among many groups of the fungi in the phylum Basidiomycota. Characteristically, they produce shelf- or bracket-shaped fruiting bodies called conks that lie in a close planar grouping of separate or interconnected horizontal rows...
) when it is broadly attached to and extends down the stipe
Stipe (mycology)
thumb|150px|right|Diagram of a [[basidiomycete]] stipe with an [[annulus |annulus]] and [[volva |volva]]In mycology a stipe refers to the stem or stalk-like feature supporting the cap of a mushroom. Like all tissues of the mushroom other than the hymenium, the stipe is composed of sterile hyphal...
.