Alternanthera pungens aka Khaki Weed

Alternanthera pungens is in the amaranth family, called Amaranthaceae. Its native range starts in Mexico and spans tropical America. Kew lists it as a subtropical subshrub. Useful Tropical Plants calls it an herb. It may live for one year, as an annual. It may also live for years, as a perennial. That source's range account names Brazil, Peru, Ecuador and Venezuela. It is not native to Britain or Ireland. It has escaped from gardens and become a weed in many places.

The plant has many branches and grows near the ground. Its stems grow from a strong taproot. Useful Tropical Plants lists a height of about 1 foot [0.3 metres]. Its full account gives an upper height of 1.6 feet [0.5 metres]. The stems can turn woody at the base. They can also root where leaves join the stems. This helps the plant form thick mats on bare ground. Broken pieces can help a patch spread as well.

The seeds travel in burrs that catch on passing objects. Clothes and shoes can carry them to new sites. Animals, tyres and machines also move the burrs. Water can carry them over short distances. Moving fodder has spread them too. The plant also grows from seed. These ways of spreading cause concern around grazed land. It can invade native pasture and crowd out valued plants. Its deep, strong taproot makes it hard to control.

Records place this weed in dry, stony sites in India. In New Guinea, it grows on low coastal land where disturbance has occurred. There it grows by roads, in dockyards and on waste ground. It also spreads into lawns, campsites and land near homes. It can spread in stockyards and sites with heavy grazing. These records show where it grows, not tested garden care needs. The sources give no firm frost limits or bloom season.

People sometimes gather wild plants for local use as medicine. Some traditional treatments aim to boost urine flow. People have also taken a boiled form to treat gonorrhoea. These reports do not prove that either treatment works or is safe. Useful Tropical Plants records no known food use or other use. It also notes suspected harm to farm stock. Reports link the plant with pig deaths and gut trouble in cattle. They also link it with inflamed skin in cattle.