Flowering plant in greenhouse


Seedlings


Seedhead

Powell Amaranth
(Amaranthus powellii, AMAPO)

U.S. Distribution: Northern and western U.S.

Line drawings of plant features

Descriptions
Seedlings:
Seed leaves are very long and narrow. First true leaves are egg-shaped. Seedlings may be deep red or green in color. As seedlings mature they become lightly hairy.

Adults: Powell amaranths are tall plants with few branches. Stems and leaves tend to be red or green and lightly hairy. Leaves are egg-shaped. Seedhead branches are few and are usually very long, thick, and prickly.

Technical Characters
Bracts long, 5-7mm. Tepals 3-5, this number often varying between flowers on a single individual, the first one or two tepals (those located immediately behind the bract) are longer than the fruit; the remaining tepals often shorter than the fruit; apices acute to acuminate, straight. Stigmas 3.

Management
Powell amaranth appears to be restricted to the northern two tiers of Iowa counties, especially in the northeast. It is a major weed in Minnesota, Wisconsin, and northern Illinois. Powell amaranth should respond to the same control strategies that are effective against redroot pigweed. Triazine resistant biotypes have been reported.