Description: Alternanthera philoxeroides, known as alligatorweed, is a native of South America and mainly invades aquatic areas. It has opposite leaves that are narrowly elliptic or spatulate and grow up to 9 cm long. The flowers of alligatorweed are round white heads on long stalks.
Ecological Threat: This plant roots in wet soils or shallow waters and can grow out into waterways. The accumulation of plants form thick mats that can cause an array of problems such as outcompeting native floral species, clogging waterways, and restricting the oxygen level of water.
Biology & Spread: These plants are highly competitive with rapid growth rates. Alligatorweed reproduces vegetatively via stolons. Each node of the plant or even fragment with a node has the ability to produce a new plant.
Threat in Oklahoma: The thick mats formed by alligatorweed can restrict flow for irrigation, inhibit fishing, result in flooding from impeded drainage, increase sedimentation, and crowd out native vegetation.