Frosted Sugarbush

Scientific Name
Protea pruinosa Rourke
Higher Classification
Common Names
Frosted Sugarbush (e)
National Status
Status and Criteria
Endangered B1ab(iii,v)+2ab(iii,v); C1+2a(i)
Assessment Date
A.G. Rebelo, H. Mtshali & D. Raimondo
Protea pruinosa has a restricted distribution range with an extent of occurrence (EOO) of 371 km², and an area of occupancy (AOO) of 60 km². The population is severely fragmented with more than 50% of the population occurring in small and isolated subpopulations. The number of mature individuals of the six known subpopulations continue to decline for unknown reasons but is likely due to too high frequency of fires in the Swartberg, and a sensitivity to drought conditions possibly linked to climate change. There are an estimated 500-1000 mature individuals extant, no subpopulation has been recorded to have more than 250 mature individuals and the population has declined by 30-50% in the past two generations 1985-2020. It therefore qualifies for listing as Endangered under criteria B and C.
South African endemic
Provincial distribution
Western Cape
This species is endemic to the Swartberg Mountains in the Western Cape Province, South Africa.
Habitat and Ecology
Major system
Major habitats
Swartberg Altimontane Sandstone Fynbos
It occurs in rocky areas, on peaks and ridges at 1600-2300 m. Mature individuals are killed by fires, and only seeds survive. Wind-dispersed seeds are stored in fire-resistant inflorescences, and released after fires. It is pollinated by rodents. This species is suspected to be slow to mature and has a generation length of 20 years. Seeds need freezing temperatures to germinate.
A total of 10% mortality of plants in the populations was observed in 1999-2001. The cause of decline is unknown but is possibly from too frequent fires and sensitivity to droughts. Too frequent fires are causing ongoing habitat degradation in many parts of Swartberg, and as a reseeder, it is likely to decline and disappear in areas that are repeatedly burnt before plants reach reproductive maturity. Monitoring data between 2010 and 2020 indicate further declines of greater than 50% have taken place at the subpopulations that have been monitored.

In 1985 it was known from numerous small subpopulations over a 30 km-long area. With one outlying subpopulation on the Blesberg some 150 kms away. Surveys in 1990 revealed fewer than 500 plants in the Klein Swartberg and definitely fewer than 1000 in the wild, spread across 6 subpopulations (Berens, 1992, Vlok, 1991, 1993). Only four subpopulations were noted during the Protea Atlas Project (1992 -2002). An additional subpopulation was surveyed in 2005. The population is declining with 10% mortality observed in surveys between 1999 and 2001. Recent surveys of some subpopulations note significant declines, for example the Bleshoek summit declined from over 200 individuals in 1992 to fewer than 50 in 2017. While the isolated subpopulation at the Blesberg declined from 10-100 plants to only 1 plant in 2018. The Hoeko subpopulation has also declined from over 50 plants in the 1990s to under 20 plants in 2007. The population is considered to be severely fragmented as over 50% of subpopulations are small and isolated. Population size is between 500-1000 mature individuals, and decline is ongoing.

Population trend
All subpopulations are in the Towerkop and Swartberg East nature reserves.
Assessment History
Taxon assessed
Status and Criteria
Citation/Red List version
Protea pruinosa RourkeEN B1ab(v)+2ab(v)Raimondo et al. (2009)
Protea pruinosa RourkeRare Hilton-Taylor (1996)
Protea pruinosa RourkeVulnerable Hall et al. (1980)

Berens, C. 1992. A plethora of range extensions in the Klein Swartberg Mountains. Protea Atlas Newsletter 15:4.

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.

Manning, J.C. and Goldblatt, P. 2012. Plants of the Greater Cape Floristic Region 1: The Core Cape Flora. Strelitzia 29. South African National Biodiversity Institute, Pretoria.

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.

Vlok, J. 1991. Unrecognized rare species from the southern Cape. Protea Atlas Newsletter 9:8-9.

Vlok, J. 1993. The plight of Protea pruinosa. Veld & Flora 79:35-37.

Rebelo, A.G., Mtshali, H. & Raimondo, D. 2019. Protea pruinosa Rourke. National Assessment: Red List of South African Plants version . Accessed on 2024/04/17

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Distribution map

© D. Turner

© D. Turner

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