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Alligator weed

Alternanthera philoxeroides
Landscape: , | Plant Form:
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Alligator weed is a perennial, herb. There are different forms of this plant which grow on land and in water. Aquatic forms may be free-floating, or rooted and emergent from the water surface.

Stems are hollow. The horizontal stem that produces roots and has shoots that develop into new plants, forming dense interwoven mats. Severe frosts may kill exposed stems.

Leaves are without stalks, dark green, smooth, waxy, 2-7 cm long, 5-40 mm wide, in pairs opposite each other on the main stems. Veins from the central rib are visible beneath the waxy leaf surface.

Flowers have silvery white heads 1.2 to 1.4 cm on stalks 2-7 cm long growing from between leaves and main stems; produced from January to March.

Fragments of Alligator weed stems are capable of producing new growth. Seed production has not been observed in Australia.

Habitats are fresh water wetlands, riverbanks and creeks. Can grow terrestrially

 

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