Amaranthus blitoides

West American amaranth ( Amaranthus blitoides )

The West American West American amaranth or pigweed ( Amaranthus blitoides ) is a species of the genus Amaranthus ( Amaranthus ) within the family of Amaranthaceae ( Amaranthaceae ). It is a weed in North America, his American common name is " prostrate pigweed ". In Europe, South America and other regions, he is a naturalized neophyte. The species occurs in Central Europe quite rare in open waste places and along riverbanks before and has no economic importance, as opposed to other Amaranthus species it does not apply here as " invasive".

Description

The North American amaranth is an annual herbaceous plant whose stems to ascending and richly branched from the foundation are prostrate and reach lengths of ( 0.1 ) 0.2 to 0.6 ( to 1 ) m. The stem is whitish, soft and not woody; it can be hairy upper ward fluffy or even bald. The leaves are petiolate, the petiole is about half as long as the dark green leaf blade. This is obovate, elliptic or spatulate, measuring 1 to 2 ( to 4) × 0.5 to 1 (up to 1.5 ) cm. The reason is wedge-shaped, the margins are usually quite flat or rarely slightly wavy, with a narrow white cartilaginous hem, the tip is blunt and rounded (but not emarginate ) and shortly mucronate.

The flowers are getrenntgeschlechtig, but sit on the same plant ( monoecious ) you sit crowded in axillary, glomerular inflorescences. The bracts of the female flowers are small, thin and with 1.5 to 5 mm in length about equal in length or slightly longer than the ( three or ) four to five tepals. These are narrow ovate to broadly linear, 1.5 to 3 mm long and more or less unequal, thin and pointed to acuminate. The style branches are apart. There are three scars present. The male flowers are mixed among the female; they have three (rarely four) tepals and three stamens.

The regular aufreißenden lid capsules are broadly ovate, 1.7 to 2.5 mm the same length as the tepals and mostly smooth, but slightly warty in the dry state or wrinkled. The black matte rather seeds are lenticular lens to broadly shaped and have a diameter of 1.3 to 1.6 mm.

From the shape rich Amaranthus blitum unweaned inflorescence and at the top is not ausgerandeten foliage leaves is the way to the leafy to tip, distinguishable. Most other similar species have only two to three flowers ( perianth ) leaves. All related, qualifying for a possible confusion species in question are dealt with in Hügin (1987).

The chromosome number is 2n = 32

Ecology

The North American foxtail is a summer and fall bloomer; in Central Europe extends the bloom season from July to October. Fertilization occurs most predominantly by self-pollination, the inconspicuous flowers have no effect on luring pollinators. The seeds have no marked distribution facilities and can because of their weight a few meters are dispersed by the wind, they are probably mostly abducted by animals ( by humans or ); they survive passage through the gut, viable seeds could be detected, for example in the dung of sheep. They can survive for several years in the ground and build a permanent seed bank on. The seeds germinate from late spring to late summer (heat Keimer ), preferably at temperatures above 25 ° C. The plant flowers and bears fruit in the same year, it is not frost-hardy, the stem shrivels and falls apart at the first frost.

The North American fox tail is a host species of parasitic thyme silk ( Cuscuta epithymum ).

Occurrence

The North American fox tail is spread almost all over North America ( not, as the German common name would suggest, just to the west ). She comes across the United States with the exception of the extreme south (Florida and southern Texas ) before, in Canada only in the southern provinces, where it was probably first introduced to the railway construction.

The North American fox tail is abducted almost worldwide in all regions of subtropical or warmtemperatem climate. According Central Europe it was probably with the transport of goods, introduced. Although for about 100 years finds present in harbors and cotton mills, he came first, before just fickle. In fact, the naturalized species, for example, since 1984 is probably only since the 1980s, in Frankfurt. Fund evidence in Germany shows the distribution map at FloraWeb.

In North America, the American West foxtail comes in disturbed habitats such as roadsides, river banks, railroads, fields, fallow land and sand surfaces from up to an altitude of 2200 m. Starting from rail and port facilities, he settled in Central Europe similar locations. In the phytosociological system he is in Germany characteristic species of the association Eragrostio - Amaranthetum blitoidis, the ruthenicae to Salsolion Association and belongs to the order Sisymbrietalia. The North American Foxtail requires nitrogen-rich, not too dry, open soils and is not shade tolerant.

System

The North American fox tail belongs to the section Blitopsis, a group of nondescript, quite similar to each other and elusive amaranth species. The first description as Amaranthus blitoides in 1877 by Sereno Watson.

There are two infraspecific units to be construed according to the American tradition as varieties:

• Amaranthus blitoides var blitoides has something fleshy, shorter leaves with broadly rounded tip.
• Amaranthus blitoides var reverchonii Uline & WLBray contributes slightly thinner, longer leaves ( length to width ratio greater than 2:1 ), which are tapered slightly at the end.

Hybrids are known with Amaranthus albus: Amaranthus × budensis, they are in appearance between the parents.

Economic Importance

The seeds of Amaranthus blitoides were harvested by the people of Zuni and ground into flour, similar to the better known and more used Kiwicha South America.

In fields of West American amaranth occurs rather infrequently, he has a weed relatively insignificant, but can in root crop cultures occur under tree crops and in gardens. The species has developed against a number of commercially available herbicides resistance.

Swell

• Sergei L. Mosyakin, Kenneth R. Robertson: Amaranthus. In: Flora of North America Editorial Committee ( eds.): Flora of North America North of Mexico. Volume 4: Magnoliophyta: Caryophyllidae, part 1, Oxford University Press, New York / Oxford et al 2003, ISBN 0-19-517389-9, p 434 (online, with illustration).
• Ulf Schmitz: identification key for the genus Amaranthus in Germany. In: Species-, determination aids, teaching and learning materials for biodiversity. November 13, 2012, accessed on 24 October 2013.
• Werner Roth painter ( Lim. ), Rudolf Schubert, Walter Vent (ed.): Excursion Flora of Germany. Volume 4: Critical band. 8th edition. Volk und Wissen, Berlin 1990. ISBN 3-06-012526-0.