Proatriplex pleiantha

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Proatriplex pleiantha
Systematics
Order : Clove-like (Caryophyllales)
Family : Foxtail family (Amaranthaceae)
Subfamily : Chenopodioideae
Tribe : Atripliceae
Genre : Proatriplex
Type : Proatriplex pleiantha
Scientific name of the  genus
Proatriplex
( WA Weber ) Stutz & GL Chu
Scientific name of the  species
Proatriplex pleiantha
( WA Weber ) Stutz & GL Chu

Proatriplex pleiantha (Syn. Atriplex pleiantha ) is the only kind of the monotypic plant genus Proatriplex , from the subfamily Chenopodioideae in the family of the foxtail plants (Amaranthaceae). The species, which was temporarily placed in the genus Atriplex , occurs in western North America and is called "Four-corners orach".

description

Appearance and leaves

Proatriplex pleiantha is an annual herbaceous plant that reaches heights and widths of 5 to 17 centimeters. The plants are bare, sometimes slightly floury. The upright shoot axes are branched from the base with white-yellowish or reddish, ascending side branches.

The alternate, sometimes almost opposite, leaves have a petiole. Their light green, fleshy leaf blades are ovate to almost circular with a length and width of 5 to 28 millimeters. The leaf margin is entire. The leaf anatomy corresponds to the "normal" (non-wreath) type of C3 plants .

Inflorescences and flowers

Proatriplex pleiantha is monoecious ( monoecious ) separate sexes. The inflorescences contain either mixed male and female flowers, or consist of terminal, interrupted false spikes with clusters of male flowers and female flowers in the leaf axils.

The male flowers (without bracts) have an inflorescence consisting of five tepals 1 to 1.5 millimeters long with a hood-like tip connected to one another in the lower half . In front of the tepals there are five stamens that arise from a discus . The anthers protrude from the flower. The female flowers are in groups of two to six between two continue reading (Brakteolen), they consist of a zarthäutigen perianth of five flaky, lanceolate to ovate Tepalen of 1 to 1.5 millimeters in length, and an ovary filamentary with two, some outstanding scars .

Proatriplex pleiantha blooms in its natural range from May to June.

Fruits and seeds

At the fruiting time, the enveloping pre-leaves grow to 3 to 7 millimeters in length and width. They are somewhat connected in the lower half. Their shape is triangular-ovoid to rounded, sitting at the base or very short stalked and with entire margins. Their surface is bare and has no appendages. The fruit, which is enclosed by the pre-leaves, is about as long as the tepals and falls off when the fruit is ripe. It is almost spherical to obovate and compressed laterally, its membranous pericarp adheres to the seed. The vertically standing seed has a black, smooth and shiny, hard seed coat. The ring-shaped embryo surrounds the abundant floury endosperm .

Sets of chromosomes

The chromosome numbers given are n = 9 ( haploid ) and 2n = 18 ( diploid ).

Occurrence

Proatriplex pleiantha is endemic to the Navajo Basin of Arizona , Colorado , New Mexico, and Utah , where it grows at altitudes of 1,400 to 1,500 meters. The species is very common in desert habitats (badlands). It often forms pure stands on saline loamy soils of depressions or occurs together with other halophytes in salty semi-desert shrub communities.

Systematics

Proatriplex pleiantha belongs to the tribe Atripliceae of the subfamily Chenopodioideae in the family Amaranthaceae .

It was first described in 1950 as Atriplex pleiantha by William Alfred Weber (in: Madroño 10 (6): pp. 188-189), who set up a separate subgenus for this species, Atriplex sugbenus Proatriplex . 1990 Howard Coombs Stutz and Ge Lin Chu raised Proatriplex to the rank of a genus (in: American Journal of Botany 77 (3), p. 364). In 2003 it was put back to Atriplex in the Flora of North America and only viewed as a separate section. In phylogenetic studies (Zacharias & Baldwin 2010), however, Protatriplex turned out to be independent and seems to be more closely related to other endemic genera of the Atripliceae than to Atriplex .

Synonyms of Proatriplex pleiantha (WA Weber) Stutz & GL Chu are Atriplex pleiantha W.A. Weber , Atriplex subg. Proatriplex W.A. Weber and Atriplex sect. Pleianthae S.L. Welsh .

Because Proatriplex pleiantha occurs in the four corners of the Four Corners , it is called "Four-corners orach" in North America.

swell

  • Elizabeth H. Zacharias, Bruce G. Baldwin: A Molecular Phylogeny of North American Atripliceae (Chenopodiaceae), with Implications for Floral and Photosynthetic Pathway Evolution . In: Systematic Botany 35 (4), 2010, pp. 839-857. doi : 10.1600 / 036364410X539907 (sections description, occurrence, systematics)

Individual evidence

  1. ↑ a b Stanley L. Welsh (2003): Atriplex pleiantha - text online as printed work , In: Flora of North America Editorial Committee (Ed.): Flora of North America North of Mexico . Volume 4: Magnoliophyta: Caryophyllidae, part 1 . Oxford University Press, New York / Oxford a. a. 2003, ISBN 0-19-517389-9 , pp. 345 (English).

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