alligatorweed

Alternanthera philoxeroides (Mart.) Griseb.

Description from Invasive.org

Appearance
Alternanthera philoxeroides is an emergent or rooted floating plant that invades aquatic areas and adjoining uplands throughout the southern portions of the United States. Plants have hollow stems and can grow to 3 ft. (1 m) tall.
Foliage
Opposite, elliptical leaves are thick but non-succulent and are up to 4 in. (10 cm) long.
Flowers
Flowering occurs during the summer with white, clover-like heads in the axils of the leaves.
Fruit
Fruits are very small, and single-seeded.
Ecological Threat
Alternanthera philoxeroides roots in wet soils or shallow water and grows out into waterways. Alternanthera philoxeroides can also grow terrestrially, forming smaller, tougher leaves. The thick mats can displace native vegetation and wildlife habitat, clog waterways, restrict oxygen levels of water, increase sedimentation, interfere with irrigation and prevent drainage. It is native to South America and was first introduced into the United States around 1900 in ballast water.

Resources


Selected Images from Invasive.org

View All Images at Invasive.org


Flower(s)
Chris Evans, University of Illinois, Bugwood.org
Additional Resolutions & Image Usage
Flower(s) the white flowers are arranged in stalked, short, headlike spikes, and have a style
Gary Buckingham, USDA Agricultural Research Service, Bugwood.org
Additional Resolutions & Image Usage
Foliage Opposite leaves
Rebekah D. Wallace, University of Georgia, Bugwood.org
Additional Resolutions & Image Usage
Plant(s)
James H. Miller, USDA Forest Service, Bugwood.org
Additional Resolutions & Image Usage
Foliage
Chris Evans, University of Illinois, Bugwood.org
Additional Resolutions & Image Usage
Plant(s) in flower
Chris Evans, University of Illinois, Bugwood.org
Additional Resolutions & Image Usage
Fruit(s) Fruit with attached perianth. Similar to an FNW taxon.
Julia Scher, USDA APHIS PPQ, Bugwood.org
Additional Resolutions & Image Usage
Infestation
Chris Evans, University of Illinois, Bugwood.org
Additional Resolutions & Image Usage
Infestation
Chris Evans, University of Illinois, Bugwood.org
Additional Resolutions & Image Usage
Plant(s) USDA NRCS. Wetland flora: Field office illustrated guide to plant species. USDA Natural Resources Conservation Service.
USDA NRCS PLANTS Database , USDA NRCS PLANTS Database, Bugwood.org
Additional Resolutions & Image Usage

Distribution