Scrambling, stoloniferous, aquatic or terrestrial perennial to 50 cm high, glabrous, stems hollow, to 10 m long, rooting at nodes. Leaves obovate to narrowly elliptic, 20–70 mm long, 10–20 mm wide; margins entire. Flowers in axillary or terminal subglobose spikes, 8–10 mm long, pedunculate; peduncle to 5 cm long; bracts and bractoles ovate, acute to accuminate, c. 3 mm long; tepals equal, elliptic, 4–6 mm long, white; anthers 5, staminodes 5. Fruit not seen. Flowers Sept.–Mar.
VVP, VRiv, GipP, OtP, WaP, Gold, CVU, NIS, HSF, Strz. Also naturalised Qld, NSW, ACT. Native of South America. Weed of urban waterways around Melbourne and regional centres (e.g. Bendigo, Warragul).
Alligator Weed is a state prohibited weed in Victoria and a declared noxious weed in Australia. Infestations smother vegetation and can cause blockages in waterways. Any sightings of this species should be reported for eradication.
