Amaranthus spinosus aka Pigweed

Amaranthus spinosus is an herb in the amaranth family. It is an annual, which means it lives one year. People call it spiny amaranth or thorny amaranth. It is native from Mexico through tropical America. It now grows as a weed in many warm regions. It grows in some cooler places too. It lives by roads, in fields, and on waste ground. People gather wild plants for food and local medicinal use.

Plants grow upright and form many branches as they grow. Garden sources give a height of about 2 feet [0.6 metres]. They give a spread of about 0.7 feet [0.2 metres]. Other accounts report heights of up to 3.3 feet [1 metre]. Sharp spines line the stems and make plants hard to handle. Grazing animals avoid the spines and the plants around them. Leaves and stems serve as greens once people remove older spines.

Each plant bears both male and female flowers. Wind moves the pollen, but plants can also fertilise themselves. PFAF gives a bloom time of July to September. In that account, seeds ripen from August to October. The small seeds measure about one millimetre across. Yet one plant can yield over 100,000 seeds. One report records almost 250,000 seeds from one plant. Warm weather and rain can bring new seedlings in repeated waves.

To grow it, choose a warm, sheltered spot in full sun. It prefers rich soil that drains well. It grows in sand, loam, and clay soils. It also accepts mildly acid, neutral, and mildly alkaline soil. It grows best in moist soil but copes with drier ground. Wet soil suits it if it does not stay waterlogged. PFAF lists USDA zones 4–11. Sow seeds outdoors in late spring, once the soil is warm. Sow earlier under glass, then plant out after the last frost.

People can eat the leaves and stems raw or cooked. They eat the seeds cooked, and these are easy to gather. Avoid food plants grown with chemical fertilisers due to the reported nitrate risk. People have used this plant to treat bleeding, diarrhoea, and wounds. These reports do not prove that the treatments work. The plant also yields materials for yellow, green, and red colours. Its large seed crop makes it a serious pasture weed. Insects chew its leaves, and it can host crop pests.