Vittadinia triloba and Rumex acetosella communities in the semi-arid regions of the South Island

Floristics of Vittadinia triloba communities in Central Otago and the upper Waitaki valley and Rumex acetosella communities in the upper Waitaki, are compared with each other and with similar communities elsewhere in the South Island. Many species are common to all semi-arid areas, but each area has as its own special features, either the presence of a particular species or the greater abundance of a widespread species. The recent increase in Vittadinia triloba is thought to be due to a combination of reduced rabbit grazing pressure, changing land and stock management and recent droughts.