Common names (selected) English: calaloo, needle burr, pigweed, prickly callaloo, prickly callau, prickly caterpillar, prickly amaranth, spiny amaranth, spiny pigweed, sticker weed, thorny amaranth, thorny pigweed, wild callau; Chinese: 刺苋 (hedgehog); French (Haiti): epinard piquard, epinard sauvage, zépina piquant, zépinard piquant; Philippines: akum, alayon, ayantoto, gitin-giting, kalitis, kalunai, orai, tadtad; Portuguese (Brazil): bredo de espino, caruru de espino, caruru-bravo, caruru-de-espinho; Spanish: ataco espinudo (Argentina), bledo espinoso (Cuba), bledo, blero, huisquilite (El Salvador), quelite (Mexico), yuyo macho (Peru), blero espinoso, (Puerto Rico), pira brave (Venezuela)

Description: summer annual

Place of origin: Native to South and Central America. Although native to the American continent, A. spinosus can now be found in tropical and subtropical regions around the world where it is considered invasive, as well as in temperate North America.

Urban habitat: Drought-tolerant, it is common on abandoned fields, disturbed sites, roadsides, sidewalks, in foundation cracks, and waste dumps.

Ecological function: Disturbance-adapted colonizer of bare ground and absorbs nitrogen in soil.

History / human uses: A. spinosus was introduced to warmer parts of the world outside of its native range from about 1700 as a cultivated crop. Various parts A. spinosus have been used for medicinal purposes: externally, to treat ulcerated mouths, vaginal discharges, nosebleeds, and wounds. Taken internally, it has been used for treatment of internal bleeding, diarrhea, excessive menstrual bleeding, and for snake bites. The seed has been used as a poultice for broken bones and a paste of the root used for treatment of menorrhagia, gonorrhea, eczema, and colic. In Nepal, a juice of the root is used to treat fevers, urinary problems, diarrhea, and dysentery. Parts of the plant and its roots are used in Southeast Asia as treatment for a variety of ailments, including gonorrhea, breathing problems, eczema, earache, and used as a diuretic. In India, it has been used to induce abortion. The plant was also used medicinally by the Cherokee tribe in North America. Yellow and green dyes can be obtained from the whole plant. Its leaves are edible raw or cooked and is consumed in parts of Africa, especially during periods of drought.