Distephanus
Encyclopedia
Distephanus is a genus
of flowering plant
s in the family
Asteraceae
. It is described by Harold Robinson as having over 40 species and by David Mabberley as having only 34 species. These sources differ sharply in their description of the range
of the genus. Robinson has it ranging thruout Africa
and occurring also in India
and China
. Mabberley has it restricted to southeast Africa, Madagascar
, and Mauritius
.
One of its species, Distephanus qazmi
, was described only recently, in 2000. The type species
is Distepanus populifolius.
The genus Distephanus consists of tree
s, shrub
s, and vine
s. The leaves
are often trinervate. The flower
s are in terminal inflorescence
s and are usually yellow. The anthers have an appendage called a tail. The base of the style is enlarged.
The name
Distephanus is derived from Greek
and means "two crowns", a reference to the two whorls
of bristles that form the pappus
.
The genus Distephanus was established by Alexandre de Cassini
in 1817. Cassini described the type species, Distephanus populifolia in 1819. This species had originally been named Conyza populifolia by Jean-Baptiste Lamarck
in 1786.
Distephanus has usually been placed in the tribe Vernonieae
, but the results of some molecular phylogenetic studies of DNA sequence
s have cast doubt upon this placement. In one classification
of Asteraceae, it was placed in a tritomy
consisting of Distephanus, Moquinieae, and Vernonieae
.
Distephanus differs from (other) genera in Vernonieae in having yellow flowers as well as in other characters that are less obvious.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of flowering plant
Flowering plant
The flowering plants , also known as Angiospermae or Magnoliophyta, are the most diverse group of land plants. Angiosperms are seed-producing plants like the gymnosperms and can be distinguished from the gymnosperms by a series of synapomorphies...
s in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Asteraceae
Asteraceae
The Asteraceae or Compositae , is an exceedingly large and widespread family of vascular plants. The group has more than 22,750 currently accepted species, spread across 1620 genera and 12 subfamilies...
. It is described by Harold Robinson as having over 40 species and by David Mabberley as having only 34 species. These sources differ sharply in their description of the range
Range (biology)
In biology, the range or distribution of a species is the geographical area within which that species can be found. Within that range, dispersion is variation in local density.The term is often qualified:...
of the genus. Robinson has it ranging thruout Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
and occurring also in India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
and China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
. Mabberley has it restricted to southeast Africa, Madagascar
Madagascar
The Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...
, and Mauritius
Mauritius
Mauritius , officially the Republic of Mauritius is an island nation off the southeast coast of the African continent in the southwest Indian Ocean, about east of Madagascar...
.
One of its species, Distephanus qazmi
Distephanus qazmi
Distephanus qazmi is a species of flowering plant in the Asteraceae family.It is found only in Yemen.-References:* Miller, A. 2004. . Downloaded on 20 July 2007....
, was described only recently, in 2000. The type species
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
is Distepanus populifolius.
The genus Distephanus consists of tree
Tree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
s, 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 vine
Vine
A vine in the narrowest sense is the grapevine , but more generally it can refer to any plant with a growth habit of trailing or scandent, that is to say climbing, stems or runners...
s. The leaves
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
are often trinervate. The flower
Flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...
s are in terminal inflorescence
Inflorescence
An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...
s and are usually yellow. The anthers have an appendage called a tail. The base of the style is enlarged.
The name
Botanical name
A botanical name is a formal scientific name conforming to the International Code of Botanical Nomenclature and, if it concerns a plant cultigen, the additional cultivar and/or Group epithets must conform to the International Code of Nomenclature for Cultivated Plants...
Distephanus is derived from Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
and means "two crowns", a reference to the two whorls
Whorl (botany)
In botany, a whorl is an arrangement of sepals, petals, leaves, or branches in which all the parts are attached at the same point and surround or wrap around the stem.There are four whorls in a general flower...
of bristles that form the pappus
Pappus (flower structure)
The pappus is the modified calyx, the part of an individual disk, ray or ligule floret surrounding the base of the corolla, in flower heads of the plant family Asteraceae. The pappus may be composed of bristles , awns, scales, or may be absent. In some species, the pappus is too small to see...
.
The genus Distephanus was established by Alexandre de Cassini
Alexandre de Cassini
Count Alexandre Henri Gabriel de Cassini was a French botanist and naturalist, who specialised in the sunflower family ....
in 1817. Cassini described the type species, Distephanus populifolia in 1819. This species had originally been named Conyza populifolia by Jean-Baptiste Lamarck
Jean-Baptiste Lamarck
Jean-Baptiste Pierre Antoine de Monet, Chevalier de la Marck , often known simply as Lamarck, was a French naturalist...
in 1786.
Distephanus has usually been placed in the tribe Vernonieae
Vernonieae
Vernonieae is a tribe of about 1300 species of plants in the aster family. They are mostly found in the tropics and warmer temperate areas, both in the Americas and the Old World. They are mostly herbaceous plants or shrubs, although there is at least one tree species, Vernonia arborea.- Taxonomy...
, but the results of some molecular phylogenetic studies of DNA sequence
DNA sequence
The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...
s have cast doubt upon this placement. In one classification
Biological classification
Biological classification, or scientific classification in biology, is a method to group and categorize organisms by biological type, such as genus or species. Biological classification is part of scientific taxonomy....
of Asteraceae, it was placed in a tritomy
Polytomy
A polytomy , meaning many temporal based branches, is a section of a phylogeny in which the evolutionary relationships can not be fully resolved to dichotomies. In a phylogenetic tree, a polytomy is represented as a node which has more than two immediate descending branches...
consisting of Distephanus, Moquinieae, and Vernonieae
Vernonieae
Vernonieae is a tribe of about 1300 species of plants in the aster family. They are mostly found in the tropics and warmer temperate areas, both in the Americas and the Old World. They are mostly herbaceous plants or shrubs, although there is at least one tree species, Vernonia arborea.- Taxonomy...
.
Distephanus differs from (other) genera in Vernonieae in having yellow flowers as well as in other characters that are less obvious.
External links
- Distephanus At: Index Nominum Genericorum At: References At: NMNH Department of Botany At: Research and Collections At: Smithsonian National Museum of Natural History
- Classification (compositae book, chapter 11 At: The International Compositae Alliance
- CRC World Dictionary of Plant Names: D-L At: Botany & Plant Science At: Life Science At: CRC Press