Alternanthera philoxeroides: Alligator weed

Family: Amaranthaceae
Common name: Alligator weed

One of the most invasive weeds that can grow on land and in water, Alligator weeds propagate very easily through fragments of the stem. The plants can grow to a height of 1 meter, with long green stems have a pink tint.

These stems are also called stolons, growing horizontally along the ground, helping the plant to spread over large areas. It can also grow and spread quickly along the sides of streams and rivers, affecting the population of fishes and other aquatic animals that will not have access to the shoreline.

The stems are hollow and snap easily. Leaves are simple, opposite, succulent, and smooth, growing to a length of 3-6 cms. Alligator weed plants produce small, ball-like, papery, white flowers that are about 1 cm in diameter.

Alligator weeds are native to South America but are now acclimatized in countries all over the world. In India, they are found on roadsides, open areas, empty plots, and agricultural areas, where they form dense mats of stems and roots, that can cover the upper surface and clog the lower surface of the soil. This can adversely affect the native vegetation that gets choked by the rampant growth of alligator weeds.

These plants are considered invasive weeds in most parts of the world, affecting plants, animals, and human activities. Since alligator weeds choke other vegetation, grazing animals are left with no food, affecting their population.

A thick growth of alligator weeds can caus waterlogging on the ground, and the blocking of shorelines affecting humans. There are many methods being tried to get rid of these nasty weeds, including manual plucking, chemicals, and biologicals methods.

The capability of alligator weeds to reproduce vegetatively from the tiniest fragments of stem make them very difficult to remove by hand.

The stems can also float in water till they find a suitable place to take root and establish themselves. This characteristic has helped alligator weeds move to new continents as well. They grow well in warm, tropical weather and high humidity.

Alligator weeds are consumed as leafy vegetables in some parts of India, but it is possible that the plant has accumulated considerable amounts of heavy metals and chemicals, since it grows on riversides and roadsides where there’s a lot of pollution.

Propagation is through stem cuttings.