|
Scientific Name | Disa arida Vlok |
Higher Classification | Monocotyledons |
Family | ORCHIDACEAE |
National Status |
Status and Criteria | Endangered C2a(i) |
Assessment Date | 2012/09/27 |
Assessor(s) | D. Raimondo, L. von Staden, W.R. Liltved & J.H. Vlok |
Justification | EOO 574 km², known from seven locations, with one recently lost due to severe infestations of alien invasive Hakea spp. Extensive monitoring of this species between 2008 and 2012 made it evident that all seven known subpopulations have fewer than 250 mature individuals. This species occurs sparsely as scattered small clumps of typically with fewer than 20 individuals. The total population is estimated to number fewer than 2000 mature individuals. Subpopulations are declining due to a deleterious fire regime and spreading dense stands of invasive Hakea spp. |
Distribution |
Endemism | South African endemic |
Provincial distribution | Western Cape |
Range | Outeniqua, Rooiberg and Gamka mountains. |
Habitat and Ecology |
Major system | Terrestrial |
Major habitats | North Rooiberg Sandstone Fynbos, North Outeniqua Sandstone Fynbos |
Description | Soil pockets or crevices in rocky outcrops of Table Mountain Sandstone on steep south-facing slopes, in arid fynbos. |
Threats |
| Threatened by invasive alien plants, one subpopulation has gone extinct due to Hakea invasion. Too frequent fire is a potential threat to this species - it only flowers in mature 20-25 year old fynbos. |
Population |
Most subpopulations surveyed are very small, numbering less than 20 mature individuals. A subpopulation at Camferskloof that has been repeatedly surveyed has fewer than 150 plants, and it is suspected that no subpopulation exceeds 250 mature individuals.
|
Population trend | Decreasing |
Assessment History |
Taxon assessed |
Status and Criteria |
Citation/Red List version | | Disa arida Vlok | EN B1ab(ii,iii,v) | Raimondo et al. (2009) | | Disa arida Vlok | VU D2 | Victor (2002) | | Disa arida Vlok | Vulnerable | Hilton-Taylor (1996) | |
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.
Hilton-Taylor, C. 1996. Red data list of southern African plants. Strelitzia 4. South African National Botanical Institute, Pretoria.
Liltved, W.R. and Johnson, S.D. Unpublished. The Cape Orchids - Wild orchids of the Cape Floral Kingdom.
Linder, H.P. and Kurzweil, H. 1999. Orchids of southern Africa. A.A. Balkema, Rotterdam.
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.
Victor, J.E. 2002. South Africa. In: J.S. Golding (ed), Southern African plant Red Data Lists. Southern African Botanical Diversity Network Report 14 (pp. 93-120), SABONET, Pretoria.
Vlok, J. and Schutte-Vlok, A.L. 2010. Plants of the Klein Karoo. Umdaus Press, Hatfield.
Vlok, J.H.J. 1985. A new Disa species (Orchidaceae) from the southern Cape. South African Journal of Botany 51(5):335-338.
|
Citation |
| Raimondo, D., von Staden, L., Liltved, W.R. & Vlok, J.H. 2012. Disa arida Vlok. National Assessment: Red List of South African Plants version . Accessed on 2025/04/14 |
Comment on this assessment
