Historical records suggest that this species was once common between Paarl and Franschhoek. After extensive habitat loss and fragmentation, it was thought to be extinct in 1976 (Rourke 1976), as the last known record dated from 1934. It was subsequently rediscovered growing among pine plantations at La Motte near Franschhoek in September 1976, and further field surveys confirmed that five isolated subpopulations remained in 1980. These subpopulations were monitored by the Protea Atlas Project between 1993 and 2001, with some follow-up monitoring by volunteers of the Custodians of Rare and Endangered Wildflowers (CREW) Programme between 2010 and 2017. At the Wemmershoek Vlei National Heritage Site, the subpopulation has remained relatively stable. In 1991 there were 20 mature individuals and several juveniles. There was a fire in 1996, but it did not impact any of the mature individuals, nor did it stimulate any germination from soil-stored seeds. Monitoring observed no fire-related population fluctuations, even though it is expected from this species' ecology. Currently, there are about five small stands of 10 to 50 plants each, with the subpopulation therefore estimated to contain about 50-250 mature individuals. The La Motte subpopulation, which was found in 1976, consisted of 2000 plants in 1980. The site, which is utilized for growing pine trees, was planted in 1971-1972, and as the pines matured and the canopy closed, the subpopulation declined to about 250 plants by 1989 (Manders 1989). A five hectare patch has been set aside for the preservation of this subpopulation, but regeneration from soil-stored seed banks were poor, and by 2001 there were still only about 200 plants surviving. This subpopulation was last monitored in 2006, when 50 plants were recorded, but the site was not thoroughly surveyed, and it is possible that up to 200 plants are still persisting at this site. At Meerlust forest station, there were initially only about 50 plants recorded, but the subpopulation increased to 100 plants when pine plantations were cleared. The site has been poorly managed and has become increasingly degraded over the years due to alien plant invasions, overgrazing and too frequent fires, and in 2001 only two plants survived when the seep they were growing in dried up. In 2005, a pipeline installed through the site eliminated the remaining plants, and since then there has been almost no regeneration from the seed bank. This subpopulation was last recorded in 2011, when there were about five plants remaining. This subpopulation is likely to be entirely lost to a low cost housing development in the near future. The largest remaining subpopulation occurs at Kleinberg south of Victor Verster prison. The site has also been under plantations, and plants occur scattered in road verges and small open patches among the pine trees. The subpopulation has been relatively stable since monitoring began in the 1990s. Currently plantation forestry is being phased out, with the site earmarked for transfer to CapeNature to be managed as a nature reserve, and the subpopulation appears to be increasing, with most recent estimates (2015) indicating that there are between 250 and 500 plants. There has however also been proposals to put the site under vineyards, based on the argument that it is too degraded for conservation as a result of historical pine plantations. However, since this is the largest remaining subpopulation, every effort should be made to restore the natural vegetation at this site. Protea Atlas Project monitoring recorded ongoing decline in the subpopulation at Kliprug, due to alien plant invasion, gravel mining and bulldozing of fire breaks. There were 200 plants in 1994, but by 1998 there were only 20-40 plants. An Environmental Impact Assessment for a golf course development failed to mention the presence of this Critically Endangered species at the site, and subsequently, the entire subpopulation was lost to development. When monitoring began in the 1980s and 1990s the remaining population of this species consisted of an estimated 2500-2700 mature individuals. Currently, there are only about 350-950 plants remaining, indicating an observed population reduction of 65-86% within 39 years, which is less than two generations for this species. If the observed rate of population decline is to continue, which is likely due to severe, ongoing threats to this species, it is likely to decline by 75-100% within three generations (45-60 years). The population is considered severely fragmented, as all remaining subpopulations are small, and occur on isolated habitat remnants. Ant dispersers are unlikely to move seeds beyond individual habitat fragments.

Goldblatt, P. and Manning, J.C. 2000. Cape Plants: A conspectus of the Cape Flora of South Africa. Strelitzia 9. National Botanical Institute, Cape Town.

Hall, A.V., De Winter, M., De Winter, B. and Van Oosterhout, S.A.M. 1980. Threatened plants of southern Africa. South African National Scienctific Programmes Report 45. CSIR, Pretoria.

Hilton-Taylor, C. 1996. Red data list of southern African plants. Strelitzia 4. South African National Botanical Institute, Pretoria.

Manders, P.T. 1989. Experimental management of a Pinus pinaster plantation for the conservation of Diastella buekii. South African Journal of Botany 55:314-320.

Raimondo, D., von Staden, L., Foden, W., Victor, J.E., Helme, N.A., Turner, R.C., Kamundi, D.A. and Manyama, P.A. 2009. Red List of South African Plants. Strelitzia 25. South African National Biodiversity Institute, Pretoria.

Rebelo, T. 2001. Sasol Proteas: A field guide to the proteas of southern Africa. (2nd ed.). Fernwood Press, Vlaeberg, Cape Town.

Rourke, J.P. 1976. A revision of Diastella (Proteaceae). Journal of South African Botany 42:185-210.