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Scientific Name | Serruria trilopha Salisb. ex Knight |
Higher Classification | Dicotyledons |
Family | PROTEACEAE |
Common Names | Trident Spiderhead (e) |
National Status |
Status and Criteria | Critically Endangered A2c |
Assessment Date | 2020/08/12 |
Assessor(s) | A.G. Rebelo, H. Mtshali, D. Raimondo & R. Koopman |
Justification | Serruria trilopha has experienced a population reduction in excess of 80% over the past three generations. This population loss is estimated based on a reduction in range (extent of occurrence), habitat loss and decline of subpopulations known through herbarium records in the past 150-300 years. There are only four viable remaining subpopulations that continue to decline due to ongoing habitat loss, alien plant invasion, invasive alien ants, overgrazing, mowing and too infrequent fires. It therefore qualifies for listing as Critically Endangered under criterion A. |
Distribution |
Endemism | South African endemic |
Provincial distribution | Western Cape |
Range | This species has a limited distribution in the Western Cape Province, South Africa, where it occurs from Malmesbury to the Cape Peninsula. It has an extent of occurrence (EOO) of 657-709 km². |
Habitat and Ecology |
Major system | Terrestrial |
Major habitats | Swartland Granite Renosterveld, Peninsula Granite Fynbos, Boland Granite Fynbos, Hangklip Sand Fynbos, Cape Flats Sand Fynbos, Atlantis Sand Fynbos |
Description | It occurs on sandy flats, 20-300 m. It is a long-lived species (generation length 50-100 years), and survives fires by resprouting from underground boles or rootstocks. Seeds are released after ripening, and dispersed by ants to their underground nests, where they are protected from predation and fire. It is pollinated by insects. |
Threats |
| Serruria trilopha's habitat has been severely transformed due to urban development, especially around Cape Town and Malmesbury. Crop cultivation for cereals and pasture is a past, and ongoing threat. Livestock grazing on remaining remnants is causing degradation of its sand fynbos habitat, as well as aiding the spread of alien invasive plants. Remaining subpopulations on road verges and under power lines are subjected to mowing, inappropriate urban fire management, especially fire exclusion. Sand mining is also causing habitat loss.
Another threat is invasive ant species that are displacing native ant species. Invasive ants do not perform the function of indigenous ants, which is to bury this species' seeds in their nests where they are protected from fire. Large scale ant invasions could lead to population collapse if there is no soil-stored seed bank to regenerate from post fire. |
Population |
This species is known from 10-20 extant, isolated subpopulations, only four of which have more than 100 plants, these occur at Lemoenkloof (on the Paardenberg), Vlakfontein, Blaauwberg, and Baasariesfontein (on the Koeberg Hill). All other subpopulations have either only one plant, or a handful of plants persisting on tiny fragments or in highly degraded habitat which is an indication that this species was once widespread across sandy lowland habitats. A population reduction in excess of 80% is inferred from habitat loss over the past three generations (150-300 years). It has been completely lost from the southern parts of the range, with no recent records from locations where it was historically recorded including Camps Bay, Fish Hoek, Raapenberg and in the area from Plumstead to Grassy Park. The population continues to decline due to ongoing habitat loss and degradation.
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Population trend | Decreasing |
Conservation |
| A few plants occur within core conservation sites on the Cape Flats but none of these are viable subpopulations, they include one plant in Plattekloof Natural Heritage Site, one plant in Klipheuwel Natural Heritage Site, and nine plants in 6 BOD Natural Heritage Site. None of the four remaining viable subpopulations are protected. |
Assessment History |
Taxon assessed |
Status and Criteria |
Citation/Red List version | | Serruria trilopha Salisb. ex Knight | CR A2c | Raimondo et al. (2009) | | Serruria trilopha Salisb. ex Knight | Endangered | Hilton-Taylor (1996) | | Serruria trilopha Salisb. ex Knight | Endangered | Hall et al. (1980) | |
Bibliography |
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.
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Citation |
| Rebelo, A.G., Mtshali, H., Raimondo, D. & Koopman, R. 2020. Serruria trilopha Salisb. ex Knight. National Assessment: Red List of South African Plants version . Accessed on 2025/05/13 |
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