''Allenrolfea'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of shrubs in the family

Amaranthaceae Amaranthaceae is a family of flowering plants commonly known as the amaranth family, in reference to its type genus ''Amaranthus''. It includes the former goosefoot family Chenopodiaceae and contains about 165 genera and 2,040 species, making it ...

. The genus was named for the English botanist

Robert Allen Rolfe Robert Allen Rolfe (1855, Wilford, Nottinghamshire – 1921, Richmond, Surrey) was an English botanist specialising in the study of orchids. For a time he worked in the gardens at Welbeck Abbey. He entered Kew in 1879 and became second assistant. ...

. There are three species, ranging from North America to South America.

Description

The species of ''Allenrolfea'' are subshrubs or shrubs with erect or decumbent growth. The stems are much branched, succulent, glabrous and appear to be articulated. The alternate leaves are sessile and stem-clasping, fleshy, glabrous, their blades reduced to small, broadly triangular scales, with entire margins and acute apex. The inflorescences are terminal spikes with spirally arranged flowers. Cymes of three or five flowers are sitting in the axils of deciduous, peltate, fleshy bracts. The flowers are bisexual. The perianth consists of 4-5 joined

tepal A tepal is one of the outer parts of a flower (collectively the perianth). The term is used when these parts cannot easily be classified as either sepals or petals. This may be because the parts of the perianth are undifferentiated (i.e. of very ...

s, their lobes angled and truncate distally. There are 1-2 stamens exserting the flower and an ovary with 2(-3) stigmas. The fruit in an ovoid, compressed utricle with membranous

pericarp Fruit anatomy is the plant anatomy of the internal structure of fruit. Fruits are the mature ovary or ovaries of one or more flowers. They are found in three main anatomical categories: aggregate fruits, multiple fruits, and simple fruits. Aggr ...

. The erect

seed A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...

is brown or reddish brown, oblong, with smooth surface. It contains copious

perisperm In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the ''integument'', forming its outer layer, the ''nucellus'' (or remnant of the megasporangium), and the fe ...

(feeding tissue), and a half-annular embryo. The chromosome basic number is x = 9.

Occurrence

The species of ''Allenrolfea'' are distributed in North America (southwestern United States), Mexico,

Central America Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...

, and

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sout ...

(

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

). They grow on alkaline soils, on sandy hummocks in salt playas, and in mud flats. In the USA they are found at about 1000–1700 m above sea level.

Systematics

The first publication of the genus ''Allenrolfea'' was made in 1891 by Otto Kuntze. With this description, he replaced the invalid name ''Spirostachys'' from 1874, (which is illegitimate, as '' Spirostachys'' already existed since 1850). The type species is ''Allenrolfea occidentalis''. The genus consists of three species: *''

Allenrolfea occidentalis ''Allenrolfea occidentalis'', the iodine bush, is a low-lying shrub of the Southwestern United States, California, Idaho, and northern Mexico.Shultz, L.M.: 'eFloras 2008''Allenrolfea occidentalis'' in Flora of North America Missouri Botanical Ga ...

'' , in North America (southwestern USA: Arizona, California, Idaho, New Mexico, Nevada, Oregon, Texas, Utah), and in Mexico. *'' Allenrolfea patagonica'' ,

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

. *'' Allenrolfea vaginata'' , endemic to Argentina. ''Allenrolfea'' is a near relative of the genus '' Heterostachys'', which also is distributed in America. Their common lineage seems to have evolved early in the evolution of the subfamily

Salicornioideae The Salicornioideae are a subfamily of the flowering plant family Amaranthaceae (''sensu lato'', including the Chenopodiaceae). Important characters are succulent, often articulated stems, strongly reduced leaves, and flowers aggregated in thick, ...

, dating back to the Early to Middle Oligocene. It might have reached America long before the other American taxa of Salicornioideae.

References

Kadereit, G., Mucina, L., & Freitag, H.: ''Phylogeny of Salicornioideae (Chenopodiaceae): diversification, biogeography, and evolutionary trends in leaf and flower morphology'', In: ''Taxon'', Volume 55 (3), 2006, p. 624, 635. Kuntze, C.E.O.: ''Revisio Generum Plantarum'' 2, 1891, p. 545-546
first description scanned at BHL
/ref> Shultz, L.M.: 'eFloras 2008
''Allenrolfea'' in Flora of North America
Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA. F.O. Zuloaga, O. Morrone, M.J. Belgrano, C. Marticorena, E. Marchesi. (Hrsg.) 2008. ''Catálogo de las plantas vasculares del Cono Sur.'' Monogr. Syst. Bot. Missouri Bot. Gard. 107(1–3): i–xcvi, 1–3348
''Allenrolfea patagonica''
F.O. Zuloaga, O. Morrone, M.J. Belgrano, C. Marticorena, E. Marchesi. (Hrsg.) 2008. ''Catálogo de las plantas vasculares del Cono Sur.'' Monogr. Syst. Bot. Missouri Bot. Gard. 107(1–3): i–xcvi, 1–3348
''Allenrolfea vaginata''

External links

* *
USDA Plants Profile

Illustration of ''Allenrolfea patagonica'' at ''Instituto de Botanica Darwinion''

Illustration of ''Allenrolfea vaginata'' at ''Instituto de Botanica Darwinion''
{{Taxonbar, from=Q3736031 Amaranthaceae Amaranthaceae genera