Acanthospermum hispidum aka Bristly Starbur

Acanthospermum hispidum belongs to the daisy family, Asteraceae. It is an annual, so it lives for one year. Its common name is bristly starbur. Kew gives tropical America as its native range. Useful Tropical Plants places it from Argentina north into Central America. This range includes Honduras and Nicaragua. Kew links it with tropical climates that have dry seasons. It grows upright to about 0.7–2.6 feet [0.2–0.8 metres]. The same account also gives a height of 1.6 feet [0.5 metres].

This plant grows where people or livestock disturb the land. Sites include upland crop fields, pastures, and ground beside roads. It grows on waste ground and near animal pens. It also grows by rail lines and cattle paths. Its growth in these places reflects its role as a weed. The source describes plants that grow in the wild. People collect them for use in folk medicine. The account gives no separate height range for garden plants.

It can grow in temperate climates and in the tropics. It grows in many soils but prefers lighter ground. It can grow in heavy clay as well. The evidence gives no exact frost limit or hardiness zone. It does not state light needs or how much water to give. The account says growers can raise it from seed. The plant makes many seeds. This helps it spread from one site to others.

Its fruits have hooked hairs that catch on animal coats. The animals then carry the fruits to new places. Seeds float, so floodwater can move them too. Bristly starbur is now a weed in tropical and subtropical regions. It invades pasture and can crowd out native plants there. It harms crops and fouls wool. Some areas class it as a noxious weed. Its leaves and seeds hold phenolic acids. These acids can curb other plants' growth. This adds to the harm its spread can cause.

People gather this bitter, scented plant for folk remedies. In parts of South America, they use it to increase urine flow and sweating. These are records of use, not proof that it helps health. Useful Tropical Plants lists no food use or other practical use. It lists no known hazards either. This does not mean the plant is safe to eat.