The Metallic Sun-orchid (Thelymitra epipactoides) and Wimmera Spider-orchid (Caladenia lowanensis) are two of Australia's most endangered plants, listed under the Victorian Flora and Fauna Guarantee Act (1998) and the federal Environment Protection and Biodiversity Conservation Act (1999). A significant population of both species exists within a reserve near Nhill in western Victoria. However, they are both under threat from invasion of the introduced weed Perennial Veldt Grass (Ehrharta calycina).

This project has protected both orchid species from becoming extinct by treating Perennial Veldt Grass in the the reserve with the chemical Verdict which has been shown to be effective against Perennial Veldt Grass but not harmful against non-grasses, bulbs and orchids. This work has also benefited the federally Endangered but less rare Greencomb Spider-orchid (Caladenia tensa) also located within the reserve.

The ANPC and Parks Victoria Little Desert Region have collaborated under a Victorian Government Communities for Nature grant to undertake weed control within the reserve over two years to support the National Recovery Plans for both species. The local community will provide ongoing support for the maintenance of the weed works and long term monitoring on the effects of the weed control.

The endangered Metallic Sun-orchid (Thelymitra epipactoides). (Photo: Kevin Sparrow) The endangered Wimmera Spider-orchid (Caladenia lowanensis). (Photo: Royal Botanic Gardens Victoria) Sprayed tufts of Perennial Veldt Grass in the Yellow gum / Callitris Woodland (Photo: Parks Victoria)