In South Africa and Australia, two of the three centers of species diversity, the natural habitats of these plants are undergoing a high degree of pressure from human activities. Expanding population centers (such as Queensland, Perth, and Cape Town) threaten many such habitats, as does the draining of moist areas for agriculture and forestry in rural areas. The droughts that have been sweeping Australia over the last 10 years also pose a threat to many species by drying up previously moist areas.