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Aquatic weeds



para grass

Para grass can form a thick blanket over the land and floats out over the water Photo: Greg Calvert

Para grass

Along the edges of weed-infested rivers, riverbanks are now choked under a smothering blanket of rank feral grasses.
One of the worst (particularly in the Townsville area) is South American para grass (Brachiaria mutica).
This grass was introduced for the cattle industry as fodder, using grass-filled dams known as "ponded pasture". Especially when excluded from grazing, para grass forms a tall, thick blanket over the land and floats out over the water.

Hymenachne

Hymenachne Photo: Greg Calvert

Olive hymenachne

Another grass used for ponded pasture is olive hymenachne (Hymenachne amplexicaulis).

Seed-laden floodwater has spread the grass and there have already been significant outbreaks of the weed in the Burdekin area of north Queensland. Since it can grow to a greater depth of water than para grass, it is expected to out-compete it.