Hymenachne amplexicaulis
Family: Poaceae

Growth Habit: It prefers low lying water on permanent water bodies or seasonally flooded areas. The plant’s stems float on water quite successfully.

Type of Plant: It is a stoloniferous, perennial grass which grows from 1 to 2.5 metres tall. Leaves are glossy green in colour, 10-45 cm long and are distinguishable by its characteristic stem-clasping leaf bases. Roots are produced at each node along the stolons where they contact moist soil.

Flowers: These are arranged in cylindrical panicles, 20-40 cm long, with spikelets 3-5 mm long. Flowering can occur anytime between September and May, usually during the autumn season.

Fruit/Seed: Following flowering, large numbers of viable seeds can germinate readily on waterlogged soils.

Dispersal: Due to its beneficial uses as a ponded pasture plant, graziers have grown Hymenachne from seed and stolons. Secondary dispersal occurs when run-off water takes seeds or stolons. Anecdotal evidence suggests birds are a vector of spread.

Distribution: Through its use for dry season cattle fodder, Hymenachne has been spread throughout sub tropical and tropical Queensland. Weed infestations occur on the coastal plains in North Queensland, with small infestations developing in the Northern Territory where it is used in mimosa control programs as a competitive cover crop.

Status: Hymenachne is a Weed of National Significance.

Weed Impact:

  • Hymenachne can form pure stands in the right conditions, excluding other plant species. Continued proliferation is expected to cause substantial losses to the sugar cane industry and serious damage to certain freshwater fisheries and conservation areas.

Information referenced from “Draft National Strategy for Hymenachne, Queensland Department of Natural Resources, September 2000.”