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Redroot Pigweed (Amaranthus retroflexus)

Redroot pigweed is a member of the Amaranth family. It is a non-native plant introduced from Europe or tropical America and is an annual reproducing by seed. The stem is light green, erect, stout, tough, rough-hairy, much branched and 1 to 6 feet tall with a long, somewhat fleshy, red taproot. The leaves are alternate with the lower ones ovate, about three to six inches long, pointed at the tip, dull green, rough-hairy, with prominent ribs and veins. The upper leaves are smaller, narrower, and more lance-shaped. Flowers are small, green, and densely crowded in large, bristly, simple, or branched, terminal or axillary clusters.

Redroot pigweed grows in cultivated fields, pastures, roadsides, and waste places in Colorado up to 8,500 feet. It is one of the most prominent, non-native annual plants found in cultivated fields in eastern Colorado.

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