[3] Pseudoraphis spinescens is native to floodplains in Asia and Australasia,[4] it is a C4 species, requiring seasonal cycles of prolonged, deep flooding interspersed with drying to achieve maximum growth and reproduction.

[8] In the Murray-Darling Basin, prior to regulation of the Murray River, extensive Pseudoraphis spinescens dominated floodplain marshes existed in areas that were typically seasonally flooded for 5–9 months duration in most years, to a minimum water depth of 0.5 m, and completely dry during late summer and autumn.

[13] The extent of floodplain marshes in Barmah forest has been severely reduced since European settlement, with the introduction of large grazing animals and the diversion of water from the Murray River.

[14][15] Floodplain areas previously dominated by aquatic species such as Moira grass (Pseudoraphis spinescens), common reed (Phragmites australis) and cumbungi (Typha spp.)

[18] Most significantly, the removal of the large population of feral horses in Barmah National Park is estimated to result in a 61% increase in the current extent of the Moira grass plains.