''Chrysogonum'' is a
genus
Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
of flowering plants in the family
Asteraceae
Asteraceae () is a large family (biology), family of flowering plants that consists of over 32,000 known species in over 1,900 genera within the Order (biology), order Asterales. The number of species in Asteraceae is rivaled only by the Orchi ...
. , two
circumscriptions of the genus were in use. In the broader circumscription, the genus has a discontinuous distribution, with species
native
Native may refer to:
People
* '' Jus sanguinis'', nationality by blood
* '' Jus soli'', nationality by location of birth
* Indigenous peoples, peoples with a set of specific rights based on their historical ties to a particular territory
** Nat ...
to eastern North America and
Madagascar
Madagascar, officially the Republic of Madagascar, is an island country that includes the island of Madagascar and numerous smaller peripheral islands. Lying off the southeastern coast of Africa, it is the world's List of islands by area, f ...
. In the narrower circumscription, the genus contains only species native to eastern North America.
Description
The plants are low-growing terrestrial herbs with yellow
flower heads
A pseudanthium (; : pseudanthia) is an inflorescence that resembles a flower. The word is sometimes used for other structures that are neither a true flower nor a true inflorescence. Examples of pseudanthia include flower heads, composite flowers ...
containing both
disc and ray florets. The genus is distinctive in having pistillate ray florets and staminate disk florets, and the pistil of the ray floret is fused to the adjacent phyllary as well as three paleae and their associated disk florets to form a "cypsela complex".
[
]
Taxonomy
The genus ''Chrysogonum'' was erected by Carl Linnaeus
Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...
in 1753 for the North American species ''Chrysogonum virginianum''. Seven species were accepted by Plants of the World Online
Plants of the World Online (POWO) is an online taxonomic database published by the Royal Botanic Gardens, Kew.
History
Following the Convention on Biological Diversity, the Royal Botanic Gardens in Kew launched Plants of the World Online i ...
: two further North American species, and four Madagascan species added by Jean-Henri Humbert starting in 1958.[ In 1977, a review of the genus reduced it to a single North American species with two varieties.][ A similar treatment was proposed by Nesom in 2001, although with three varieties.][ In 2020, Nesom accepted one of the varieties as a separate species, ''Chrysogonum repens''.][
]
Species
If the genus is regarded as confined to North America, there are potentially three species:[
*'' Chrysogonum australe'' , syn. ''Chrysogonum virginianum'' var. ''australe'' (Alexander ex Small) H.E.Ahles][ which may alternatively be placed in the genus '' Aspilia'':
*'' Chrysogonum leandrii'' , syn. ''Aspilia leandrii'' (Humbert)
*'' Chrysogonum madagascariense'' , syn. ''Aspilia madagascariensis'' (Humbert)
*'' Chrysogonum perrieri'' , syn. ''Aspilia perrieri'' Humbert
*'' Chrysogonum stenocephalum'' , syn. ''Aspilia stenocephala'' (Humbert)]
Former species
*''Chrysogonum trichodesmoides'' (F.Muell.) F.Muell. = '' Pentalepis trichodesmoides'' F.Muell.
Uses
''Chrysogonum virginianum'' is grown as an ornamental plant under the common name of green and gold, and is used primarily as a ground cover.[
]
References
Heliantheae
Asteraceae genera
{{Heliantheae-stub