''Heterostachys'' is a genus of

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Ancient Greek, Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed with ...

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, maki ...

. 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. ...

s native to

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a considerably smaller portion in the Northern Hemisphere. It can also be described as the southern Subregion#Americas, subregion o ...

and

Central America Central America is a subregion of North America. Its political boundaries are defined as bordering Mexico to the north, Colombia to the southeast, the Caribbean to the east, and the Pacific Ocean to the southwest. Central America is usually ...

Description

The species of ''Heterostachys'' grow as

subshrub A subshrub (Latin ''suffrutex'') or undershrub is either a small shrub (e.g. prostrate shrubs) or a perennial that is largely herbaceous but slightly woody at the base (e.g. garden pink and florist's chrysanthemum). The term is often interch ...

s or low

shrub A shrub or bush is a small to medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees by their multiple ...

s. The stems are much branched, glabrous, and not jointed. The alternate

leaves A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...

are fleshy, glabrous, scale-like, stem-clasping, with very short free blades (1–2 mm). The

inflorescences In botany, an inflorescence is a group or cluster of flowers arranged on a plant's stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a main axis ( pe ...

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. It is a structure that forms an envelope surrounding the sexual organs, consisting of the calyx (sepals) and the corolla (petals) or tepal ...

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

stamen The stamen (: stamina or stamens) is a part consisting of the male reproductive organs of a flower. Collectively, the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filament ...

s 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 Hispaniola (, also ) is an island between Geography of Cuba, Cuba and Geography of Puerto Rico, Puerto Rico in the Greater Antilles of the Caribbean. Hispaniola is the most populous island in the West Indies, and the second-largest by List of C ...

). 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'') an ...

s and salty inland habitats.

Systematics

The genus ''Heterostachys'' was first published in 1876 by

Franz Ungern-Sternberg Franz may refer to: People * Franz (given name) * Franz (surname) Places * Franz (crater), a lunar crater * Franz, Ontario, a railway junction and unorganized town in Canada * Franz Lake, in the state of Washington, United States – see Fran ...

. 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 International_Code_of_Zoological_Nomenclature, 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 spe ...

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

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

(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, is a landlocked country in South America. It is bordered by Argentina to the Argentina–Paraguay border, south and southwest, Brazil to the Brazil–Paraguay border, east and northeast, and Boli ...

Venezuela Venezuela, officially the Bolivarian Republic of Venezuela, is a country on the northern coast of South America, consisting of a continental landmass and many Federal Dependencies of Venezuela, islands and islets in the Caribbean Sea. It com ...

Peru Peru, officially the Republic of Peru, is a country in western South America. It is bordered in the north by Ecuador and Colombia, in the east by Brazil, in the southeast by Bolivia, in the south by Chile, and in the south and west by the Pac ...

Haiti Haiti, officially the Republic of Haiti, is a country on the island of Hispaniola in the Caribbean Sea, east of Cuba and Jamaica, and south of the Bahamas. It occupies the western three-eighths of the island, which it shares with the Dominican ...

Dominican Republic The Dominican Republic is a country located on the island of Hispaniola in the Greater Antilles of the Caribbean Sea in the Atlantic Ocean, North Atlantic Ocean. It shares a Maritime boundary, maritime border with Puerto Rico to the east and ...

. ''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 The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

. 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