| Scientific Name | Dioscorea brownii Schinz | Higher Classification | Monocotyledons | Family | DIOSCOREACEAE |
National Status | Status and Criteria | Endangered B2ab(i,ii,iii,iv,v); C2a(i) | Assessment Date | 2016/05/30 | Assessor(s) | A.T.D. Abbott, I.M. Johnson, G. Grieve & L. von Staden | Justification | Five small, severely fragmented subpopulations remain with an estimated Area of Occupancy of <100 km². The largest subpopulation consists of around 200 mature individuals, and the population size is estimated to number between 300 and 500 mature individuals, and continues to decline due to ongoing habitat loss and degradation. |
Distribution | Endemism | South African endemic | Provincial distribution | Eastern Cape, KwaZulu-Natal | Range | Presently at Ngele Mountain and near Richmond, but has been collected elsewhere in southern KwaZulu-Natal in the past. It possibly also occurs in the Eastern Cape. |
Habitat and Ecology | Major system | Terrestrial | Major habitats | Midlands Mistbelt Grassland, Moist Coast Hinterland Grassland, Drakensberg Foothill Moist Grassland | Description | Tall mistbelt and moist montane grassland, on high ground along forest margins, in rich, red, dolerite soils. |
Threats | Midlands Mistbelt Grassland between Weza and Richmond is already at least 70% irreversibly modified, predominantly for timber plantations. Remaining grasslands are fragmented, and continue to be degraded due to inappropriate fire management, overgrazing by livestock, and alien invasive plants. Of the four known existing locations, one is in a patch of grassland between a recently established timber plantation and an expanding rural village. The area is heavily grazed (I.M. Johnson pers. obs. 2009), and the subpopulation is likely to be severely impacted, should either the village or plantation expand any further. The second location is in a very small grassland fragment among timber plantations, and requires management and clearing of alien invasive plants. This site is also being degraded due to heavy overgrazing (I.M. Johnson pers. obs. 2009). A third subpopulation was recently recorded in a grassland fragment next to a sawmill. Although this grassland is burnt annually, it is still in good condition, and has a high species diversity (G. Grieve pers. obs. 2011). A fourth location is also in a grassland fragment adjoining expanding timber plantations. The subpopulation near Richmond occurs in a site contracted for conservation through the Biodiversity Stewardship Programme. The site is grazed by livestock, but in relatively good condition. Ongoing clearing of alien invasive plants is needed, which currently occur in low densities.
Some Dioscorea species are used medicinally, but the use of D. brownii has not specifically been reported (Arnold et al. 2002). |
Population | Dioscorea brownii was first discovered in 1883, and since then it has been rarely collected. Historical records are from a wide area stretching from the Richmond district in southern KwaZulu-Natal to Umtata in the Eastern Cape. These records however have very imprecise locality descriptions, and many have never been relocated. Since the 1970s, the species was known only from a small area on state land around Weza, southern KwaZulu-Natal. Here the species remains on small remnants of mistbelt grassland. Three small, isolated subpopulations are currently known, the largest one consisting of around 200 mature individuals, and the other two with between 10 and 50 plants. A fourth subpopulation, recorded by the local conservation authority in the same area, is likely to still exist, but survey data lacks an estimate of the subpopulation size. Recently, another small subpopulation was discovered about 80 km north of Ngele, in the Richmond district, where it was last recorded in 1946. About 100 plants occur in scattered, small clumps in mistbelt grassland fragmented by timber plantations.
This species is easily overlooked within its grassland habitat, and may be under-sampled. However, with less than 30% of its habitat remaining intact, it is unlikely that many more subpopulations exist, and all are likely to be small and confined to isolated grassland fragments. Remaining known subpopulations require ongoing monitoring. Estimating the global population size is difficult, but it is likely to be small. All known subpopulations consist of fewer than 200 mature individuals, and therefore it is unlikely that the population size exceeds 2500 mature individuals. A present the known population numbers around 400 mature individuals.
This species' Extent of Occurrence is very uncertain: historical records are from an area of over 10 000 km². Current known occurrences of this species are however confined to an area of 500-6941 km².
| Population trend | Decreasing |
Assessment History |
Taxon assessed |
Status and Criteria |
Citation/Red List version | Dioscorea brownii Schinz | EN B1ab(iii,v)+2ab(iii,v); C2a(i) | 2015.1 | Dioscorea brownii Schinz | VU D2 | Raimondo et al. (2009) | Dioscorea brownii Schinz | Data Deficient | Scott-Shaw (1999) | Dioscorea brownii Schinz | Rare | Hilton-Taylor (1996) | |
Bibliography | Abbott, T. 1998. The rediscovery of Dioscorea brownii. PlantLife 18:29.
Arnold, T.H., Prentice, C.A., Hawker, L.C., Snyman, E.E., Tomalin, M., Crouch, N.R. and Pottas-Bircher, C. 2002. Medicinal and magical plants of southern Africa: an annotated checklist. Strelitzia 13. National Botanical Institute, Pretoria.
Hilliard, O.M. and Burtt, B.L. 1976. Notes on some plants of Southern Africa chiefly from Natal: V. Notes from the Royal Botanic Garden Edinburgh 34(3):253-286.
Hilton-Taylor, C. 1996. Red data list of southern African plants. Strelitzia 4. South African National Botanical 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.
Scott-Shaw, C.R. 1999. Rare and threatened plants of KwaZulu-Natal and neighbouring regions. KwaZulu-Natal Nature Conservation Service, Pietermaritzburg.
|
Citation | Abbott, A.T.D., Johnson, I.M., Grieve, G. & von Staden, L. 2016. Dioscorea brownii Schinz. National Assessment: Red List of South African Plants version . Accessed on 2025/02/11 |
Comment on this assessment
|
 © L. von Staden
Search for images of Dioscorea brownii on iNaturalist
|