Family: Amaranth (Amaranthaceae)
Size: To 0.125 in. wide in a large, branched, spike-like terminal cluster.
Other names: Rough pigweed, carelessweed
Notes: Flower clusters are full of stiff, spine-like scales. 13 species of Amaranthus in Arizona.
Photos of this plant may be seen on the CalPhoto plant website.
Entry for redroot pigweed in the University of California Statewide Integrated Pest Management Project.
Entry for redroot pigweed in the Canadian Poisonous Plants Information System.
Redroot amaranth plant profile on the USDA Plants server.