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| Spiny amaranth (Amranthus spinosus) |
Natural History
Spiny amaranth is an annual pigweed. A member of the Amaranthaceae family which includes other plants such as joyweed, pigweed and cock's comb. The Amaranthaceae are mostly herbs and rarely shrubs or small trees comprising 65 genera and 900 species.
Spiny amaranth is an annual pigweed and can be as tall 5 feet. Its stems and leaves are hairless and can have a reddish tinge. The leaves are alternate and oval to egg shape. Spiny amaranth plants also have a pair of short spines at the base of leaf petioles.
Some pigweed plants(Amaranthus palmeri) are edible. The use pigweeds as a crop is well documented. The Aztecs cultivated amaranth as one of their crops. They made a dough out of milled amaranth and toasted corn seeds mixed with honey or maguey sap. The dough was formed into idols for various religious festivals. However, some pigweeds have been associated with nitrate accumulation is livestock and they considered toxic to cattle, goats and sheep.
Management Strategies
Mowing can suppress spiny amaranth growth. However the plant will bounce back if mowing is not maintained. For smaller stands of weeds, manually remove plants before flowering occurs and seeds are produced. Herbicides can be used on larger areas as a supplement to a cultural control program, but not as a replacement for a cultural control program.
Additional Information
Spiny Pigweed - Rutgers University
Pigweed - American Indian Health and Diet Project
Amaranthacaea - University of Hawaii
Hay Crop and Pasture Weed Management - University of Tennesse
