Manchurian wild rice

Manchurian wild rice is a very invasive, tall non-native grass that takes over areas of land and shallow water. It has been found in Northland, Auckland, Waikato and Greater Wellington regions, growing next to riparian areas of rivers, lakes and drains, in swamps and on low-lying farmland. In the Waikato region, the main infestations are adjacent to the Waihou and Piako rivers on the Hauraki Plains, and also at Pūriri, Horahora and Lake Te Ko Utu, Cambridge. Manchurian wild rice forms dense mats that keep out other plants and block drainage in waterways.

Manchurian wild rice has deep roots that can destroy stopbanks. Its root system spreads widely, and any fragment can grow into a new plant. Manchurian wild rice destroys native plant and fish habitats.

Manchurian wild rice is a highly invasive grass that forms dense long-lived stands on land and water margins, overtopping other riparian species. Causes silt to accumulate, altering water systems, leading to flooding and destroying habitat for aquatic fauna and flora. Manchurian wild rice has deep roots that can destroy stopbanks. Its root system spreads widely, and any fragment can grow into a new plant.

Rhizomes spread outwards slowly, but more rapid spread comes from seeds and rhizome fragments being moved by water, livestock, machinery, clothing and possibly by birds. Road graders, soil movement, dumped vegetation, contaminated diggers, farm machinery, eel nets, boats and trailers all spread seed and rhizome fragments into new catchments, lowland pasture, roadsides, water tables, drains and farm dams.