|Scientific Name||Amaranthus retroflexus L.|
|Common Names||English: Redroot pigweed, common amaranth; German: Zurückgebogener Amarant, rauhaariger Fuchsschwanz; French: Amarante réfléchie; Spanish: Bledo|
|Description||Annual, common seed weed, erect growth, 20-220 cm (7.87 - 86.6 inch) high depending on growing conditions.|
Compact, caespitous inflorescence.
Cotyledons longoval, 10-12 mm (0.39 - 0.47 inch), at the underside often redviolet.
Erect, single or branched, light green to reddish, more or less short and rough hairy.
Long petiolate leaves, ovate, pointed, gray-green.
Borne in short, dense, sometimes branched spikes up to 20 cm (7.87 inch) long, green, each flower unisexual but with both the male and female flowers on the same plant.
Bracts about 6.5 cm (2.56 inch) long, longer than the sepals.
Urticle, nearly globe-shaped, slightly rugose.
Germination from late spring-summer. Seeds are lentiform, dark red-brown and shiny.
Viability of Seeds
More than 40 years.
A. retroflexus is found on dry, disturbed ground and especially cultivated, set aside or abandoned fields and burned areas, where it is a rapid colonist.
Redroot pigweed prefers warm and fertile soils.
Additional Crop Information
Crops with late canopy closure like row crops, vegetables.
This aggressive weed is native to tropical America, but is found throughout both American subcontiments but also in Western, Central and Eastern Europe and parts of Asia. It greatly reduces yield and quality and interferes with combine harvesting. Because of its rapid growth and deep root system (more than 1 m; 39.37 inch) it competes for water and nutrition, therefore it is very resistant to drought. Redroot pigweed accumulates nitrate and may cause bloat in cattle.
Biotypes resistant to herbicides like triazines or ALS inhibitors have been discovered. A. retrofexus hybridizes with other Amaranthus species and the amaranth crop.
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