Cotula
Encyclopedia
Cotula is a genus of flowering plant
in the Asteraceae
family. It includes about 80 species of plants known generally as water buttons or buttonweeds.
The species within this genus can vary extensively in their habit
, leaf division, involucre
, receptacle and achene
s. This makes it difficult to define them by comparing their morphology
. The genus can only be defined by looking at the corollas of their flowers. Most are disciform (lacking ray florets). These corollas may be tubular, reduced or even absent. Another characteristic are their solitary heads growing on a peduncle
.
. In 1867 the genus was subdivided by George Bentham
into three sections. Since his account, only a few changes have been made but the number of species has remained more or less stable. The sections possess different basic chromosome
numbers :
David G. Lloyd has proposed that the five species from Australia and New Guinea are distinctive enough from the other species from the section Leptinella to be brought under a new section with the proposed name Oligoleima (type species C. longipes).
Only a few hybrids are known :
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...
in 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...
family. It includes about 80 species of plants known generally as water buttons or buttonweeds.
The species within this genus can vary extensively in their habit
Habit (biology)
Habit, when used in the context of biology, refers to the instinctive actions of animals and the natural tendencies of plants.In zoology, this term most often refers to specific behavioral characteristics, even when directly related to physiology...
, leaf division, involucre
Involucre
Involucre may refer to* involucral bract, a bract, bract pair, or whorl of bracts surrounding a flower or inflorescence* a term sometimes misused for the cupule surrounding developing nuts in the Fagaceae...
, receptacle and achene
Achene
An achene is a type of simple dry fruit produced by many species of flowering plants. Achenes are monocarpellate and indehiscent...
s. This makes it difficult to define them by comparing their morphology
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
. The genus can only be defined by looking at the corollas of their flowers. Most are disciform (lacking ray florets). These corollas may be tubular, reduced or even absent. Another characteristic are their solitary heads growing on a peduncle
Peduncle (botany)
In botany, a peduncle is a stem supporting an inflorescence, or after fecundation, an infructescence.The peduncle is a stem, usually green and without leaves, though sometimes colored or supporting small leaves...
.
Taxonomy
Cotula is the largest genus found in the Southern Hemisphere of the tribe Anthemideae. This genus was first mentioned by Carl Linnaeus, who described four species in his first edition (1753) of Species PlantarumSpecies Plantarum
Species Plantarum was first published in 1753, as a two-volume work by Carl Linnaeus. Its prime importance is perhaps that it is the primary starting point of plant nomenclature as it exists today. This means that the first names to be considered validly published in botany are those that appear...
. In 1867 the genus was subdivided by George Bentham
George Bentham
George Bentham CMG FRS was an English botanist, characterized by Duane Isely as "the premier systematic botanist of the nineteenth century".- Formative years :...
into three sections. Since his account, only a few changes have been made but the number of species has remained more or less stable. The sections possess different basic chromosome
Chromosome
A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...
numbers :
- section Cotula : largest section with about 40 species; mostly in South Africa, a few in North Africa and Australia + the cosmopolitan species C. coronopifolia and the widespread species C. turbinata; this section also includes the former genera Cenia and Otochlamys; basic chromosome numbers x = 8 and x = 10.
- section Strongylosperma (Less.) Benth.: a total of eight species, found in warmer parts of Africa and Asia (often lumped as C. anthemoides), Central and South America (C. mexicana) and Australia (five species, including C. australis); basic chromosome number : x = 18
- section Leptinella (Cass.) Hook f. : the remaining thirty species, found in South America and the Falkland Islands (the type species C. scariosa), New Zealand, the Subantarctic Islands (together 24) and five species from Australia and New Zealand.; the species in this section have a distinctive charactersitic not found in the other sections : inflated pistillate corollas; basic chromosome number : x = 13. See also LeptinellaLeptinellaLeptinella is a genus of alpine flowering plant in the Asteraceae family, comprising 33 species, distributed in New Guinea, Australia, New Zealand, the Subantarctic Islands, and South America....
.
David G. Lloyd has proposed that the five species from Australia and New Guinea are distinctive enough from the other species from the section Leptinella to be brought under a new section with the proposed name Oligoleima (type species C. longipes).
Selected species
- Cotula albida
- Cotula alpina
- Cotula anthemoides
- Cotula atrata
- Cotula australisCotula australisCotula australis is a species of plant in the daisy family known by the common names southern waterbuttons and Australian waterbuttons. This small plant is native to Australia and New Zealand, but it is known in other areas of the world as a common weed. The plant grows low to the ground in a thin...
- Cotula calcarea
- Cotula cinerea
- Cotula coronopifoliaCotula coronopifoliaThe small marsh flower Cotula coronopifolia bears the common names brass buttons, golden buttons, and buttonweed. The flowers are bright yellow discoid inflorescences that look like thick buttons. Individual plants spread stems along the ground and send up the knobby flowers at intervals...
- Cotula dendyi
- Cotula dioica
- Cotula dispersa
- Cotula featherstonii
- Cotula filiformis
- Cotula goyenii
- Cotulla intermedia
- Cotula lanata
- Cotula longipes
- Cotula maniototo
- Cotula mexicana
- Cotula minor
- Cotula moseleyiCotula moseleyiCotula moseleyi, also known as Nightingale Brassbuttons, is a species of flowering plant in the Asteraceae family. It is found in Tristan da Cunha. Its natural habitats are subantarctic forests, subantarctic grassland, rocky shores, and ....
- Cotula nana
- Cotula pectinata
- Cotula perpusilla
- Cotula plumosaCotula plumosaCotula plumosa is a small flowering plant in the daisy family, in a genus the members of which are often called buttonweeds. It is a circumantarctic species found on many subantarctic islands in the Southern Ocean...
- Cotula potentillina
- Cotula pyrethrifolia
- Cotulla rotundata
- Cotula rotundifolia
- Cotula scariosa (type species of section Leptinella)
- Cotula serrulata
- Cotula squalida
- Cotula traillii
- Cotula turbinata
Only a few hybrids are known :
- Cotula dendyi × Cotula atrata
- Cotula albida × Cotula pectinata
Further reading
- Jakubowsky, G. and L. Mucina. (2007). Phylogeny of the South African centred plant genus Cotula (Asteraceae). South African Journal of Botany 73:2 292.