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Alternanthera philoxeroides

Description: native to South America and invades aquatic areas including lake margins and river banks. 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 or across land.  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.


In Oklahoma:  The McClellan-Kerr Navigation channel has been impacted by a significant infestation of alligator weed.

Management: Aquatic Weed Management, OSU Extension Factsheet


Additional Information: Problem Horticultural Plants, OSU Extension Factsheet

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