Also called Redroot pigweed. Annual seed-propagated weed germinating late in the spring or in the summer reaching a height of 15 to 130 cm. Optimal germination temperature is 20 to 40 °C. Predominantly grows on loose, well-drained, nutrient- and especially nitrogen-rich humus-rich soils with good tilth. Especially in climatically favorable areas, red-root amaranth is a very competitive weed that has been spreading further north is recent years. Introduced to Europe at the end of the 19th century from North America.
The cotyledons are elongated-oval, rounded at the tip, gradually becoming narrower towards the petiole (Picture 1). The midrib is clearly visible on the underside of the cotyledons. The leaves are egg-shaped with a long petiole, grayish bluish green, alternate and pointed at the tips (Picture 2). The stem, petiole and the underside of the leaves are often red-purple in color. The flower clusters are grouped in short, dense greenish flower spikes with spiny bracts (Picture 3). The seeds are black and shiny, lenticular (Picture 4) and remain viable in the soil for many years. One plant produces between 1,000 and 5,000 seeds. Germination can take place above 7 to 12 °C, optimally above 20 to 25 °C.