''Heterostachys'' is a genus of

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

s in the plant 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 two species are shrubby

halophyte A halophyte is a salt-tolerant plant that grows in soil or waters of high salinity, coming into contact with saline water through its roots or by salt spray, such as in saline semi-deserts, mangrove swamps, marshes and sloughs and seashores. Th ...

s native to

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 ...

and

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. ...

Description

The species of ''Heterostachys'' grow as subshrubs or low shrubs. The stems are much branched, glabrous, and not jointed. The alternate leaves are fleshy, glabrous, scale-like, stem-clasping, with very short free blades (1–2 mm). The

inflorescences 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. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed ...

are orbicular to cone-like, with alternate to nearly opposite scale-like bracts, and with one free flower sitting in the axil of each bract. The flowers are bisexual. The four-lobed

perianth The perianth (perigonium, perigon or perigone in monocots) is the non-reproductive part of the flower, and structure that forms an envelope surrounding the sexual organs, consisting of the calyx (sepals) and the corolla ( petals) or tepals when ...

consists of four half-connate unequal

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. There are two stamens and an ovary with two stigmas. In fruit the perianth becomes thick and spongy. The fruit wall (pericarp) is membranous. The seed is lenticular to edge-shaped with tuberculate surface. It contains a semi-annular embryo and copious perisperm (feeding tissue).

Distribution and habitat

''Heterostachys'' is distributed in

and

( Hispaniola). The plants are

s and grow in coastal

lagoon A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' (or ''barrier lagoons'') ...

s and salty inland habitats.

Systematics

The genus ''Heterostachys'' was first published in 1876 by Franz Ungern-Sternberg. With this description, he replaced the invalid name ''Spirostachys'' Ung.-Sternb. from 1866, (which is illegitimate, as '' Spirostachys'' Sond. already existed since 1850). The

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specime ...

is ''Heterostachys ritteriana''. The genus comprises two species: *'' Heterostachys olivascens'' (Speg.) Molfino - endemic to

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 ...

(Buenos Aires, Mendoza, Río Negro), at 0–500 m above sea level. *'' Heterostachys ritteriana'' (Moq.) Ung.-Sternb. - widely distributed in South America and Central America:

Paraguay Paraguay (; ), officially the Republic of Paraguay ( es, República del Paraguay, links=no; gn, Tavakuairetã Paraguái, links=si), is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to th ...

Venezuela Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in th ...

Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = National seal , national_motto = "Firm and Happy f ...

, Haiti,

Dominican Republic The Dominican Republic ( ; es, República Dominicana, ) is a country located on the island of Hispaniola in the Greater Antilles archipelago of the Caribbean region. It occupies the eastern five-eighths of the island, which it shares with ...

. ''Heterostachys'' is closely related to the genus '' Allenrolfea'', 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

Gudrun Kadereit, Ladislav Mucina & Helmut Freitag: ''Phylogeny of Salicornioideae (Chenopodiaceae): diversification, biogeography, and evolutionary trends in leaf and flower morphology'', In: ''Taxon'', Volume 55 (3), 2006, p. 623, 624, 632. Tropicos, specimen list for ''Heterostachys ritteriana'' (Moq.) Ung.-Sternb.
/ref> Franz Ungern-Sternberg: ''Salicorniearum Synopsis''. In: ''Atti del congresso internazionale botanico tenuto in Firenze nel mese di maggio 1874'', 1876, p. 331
first publication of ''Heterostachys''
/ref> Franz Ungern-Sternberg: ''Versuch einer Systematik der Salicornieen'', Inaug. Diss., Dorpat: Karow., 1866, p. 100
first publication of ''Spirostachys'' Ung.-Sternb.
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
''Heterostachys olivascens''
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
''Heterostachys ritteriana''

External links

* *
Illustration of ''Heterostachys olivascens''
at Instituto de Botanica Darwinion.

Illustrations of ''Heterostachys ritteriana'' at Instituto de Botanica Darwinion. {{Taxonbar, from=Q5896802 Amaranthaceae Amaranthaceae genera