Proatriplex

Proatriplex pleiantha (syn. Atriplex pleiantha ) is the only species of the monotypic genus Proatriplex, of the subfamily Chenopodioideae in the family of Amaranthaceae ( Amaranthaceae ). The kind that has been temporarily assigned to the genus Atriplex, is found in western North America and is called " Four Corners orach ".

• 4.1 Notes and references

Description

Appearance and leaves

Proatriplex pleiantha is an annual herbaceous plant that reaches stature heights and widths from 5 to 17 centimeters. The plants are glabrous, sometimes slightly mealy. The upright stem axis are from the base of branches with white- yellowish or reddish, ascending side branches.

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

Inflorescences and flowers

Proatriplex pleiantha is monoecious ( monoecious ) getrenntgeschlechtig. The inflorescences contain either mixed male and female flowers, or consisting of terminal, interrupted sham ears with wads of male flowers and female flowers in the leaf axils.

The male flowers (without bracts ) have a perianth of five in the bottom half of interconnected tepals of 1 to 1.5 mm in length with hood -like tip. Before the tepals are five stamens which spring from a discus. The anthers protrude from the flower. The female flowers are arranged in groups of two to six between two Down (Roll Brakteolen ), they consist of a zarthäutigen perianth of five scale-like, lanceolate to ovate tepals of 1 to 1.5 millimeters in length, and an ovary with two filiform, slightly protruding scars.

Proatriplex pleiantha flowers in her native range from May to June.

Fruit and seeds

At the time the fruit enveloping bracts grow to 3-7 mm in length and width. They are connected to each other in the lower half of a bit. Its form is triangular- ovate to roundish, sitting at the base or stalked quite short and entire. Their surface is bare and has no appendages on. The fruit, which is enclosed by the Page Down is about as long as the tepals and drops to fruit ripening. She is compressed almost spherical to obovate and side, their membranous pericarp adheres to the seeds. The vertically standing seed has a black, smooth and glossy, hard seed coat. The annular surrounds the embryo abundant mealy endosperm.

Sets of chromosomes

As chromosome numbers n = 9 ( haploid) and 2n = 18 (diploid ) can be specified.

Occurrence

Proatriplex pleiantha is endemic in Navajo Basin of Arizona, Colorado, New Mexico and Utah, where it grows at altitudes from 1400 to 1500 meters. The species is very common in arid habitats ( badlands ). It often forms pure stocks on salted clay soils sinks or comes together with other halophytes in saline semi-desert shrub societies.

System

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

The first description was in 1950 as Atriplex pleiantha by William Alfred Weber ( in: Madroño 10 (6): p.188 -189 ), of its own subgenus, Atriplex sugbenus Proatriplex aufstellte for this species. 1990 lifted Howard Coombs Stutz and Ge Lin Chu Proatriplex to the rank of genus ( in: American Journal of Botany 77 (3), p 364). In 2003 she was in the Flora of North America again asked to Atriplex and viewed only as a separate section. In phylogenetic studies ( Zacharias & Baldwin 2010) Protatriplex proved to be independent, and seems to be more closely related to other endemic genera of Atripliceae than with 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 at the junction of the Four Corners, it is called in North America " Four corners orach ".

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, S.839 - 857th doi: 10.1600/036364410X539907 (Sections Description, occurrence, systematics )