Are Darwinia citriodora and Chionochloa both endemic to western Australia?
no
Title: Darwinia citriodora
Passage: Darwinia citriodora, commonly known as lemon-scented darwinia or lemon scented myrtle, is a plant in the myrtle family Myrtaceae and is endemic to the south-west of Western Australia.  It is a shrub with oblong to lance-shaped leaves and red, yellow and orange flowers over an extended period.  It is a hardy plant in well-drained soil, is often cultivated and used as a rootstock for less hardy species.
Title: Chionochloa
Passage: Chionochloa is a genus of tussock grass in the "grass family", found primarily in New Zealand with one known species in New Guinea and another on Lord Howe Island (part of Australia).  Some of the species are referred to as snowgrass.
Title: Darwinia vestita
Passage: Darwinia vestita, commonly known as the pom-pom darwinia, is a plant in the myrtle family Myrtaceae and is endemic to Western Australia.
Darwinia citriodora Chionochloa