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Scientific Name | Disa lugens Bolus var. nigrescens (H.P.Linder) H.P.Linder |
Higher Classification | Monocotyledons |
Family | ORCHIDACEAE |
Synonyms | Herschelia lugens (Bolus) Kraenzl. var. nigrescens H.P.Linder, Herschelianthe lugens (Bolus) Rauschert var. nigrescens (H.P.Linder) N.C.Anthony |
National Status |
Status and Criteria | Critically Endangered B1ab(iii,v)+2ab(iii,v) |
Assessment Date | 2023/01/25 |
Assessor(s) | L. von Staden & W.R. Liltved |
Justification | This taxon is a highly restricted endemic known from one location near Humansdorp. It has an extent of occurrence (EOO) and an area of occupancy (AOO) of less than 5 km². Habitat quality is declining due to alien invasive plants. This species therefore qualifies for listing as Critically Endangered under criterion B. |
Distribution |
Endemism | South African endemic |
Provincial distribution | Eastern Cape |
Range | This taxon is endemic to the Eastern Cape Province, where it is restricted to Oyster Bay near Humansdorp. |
Habitat and Ecology |
Major system | Terrestrial |
Major habitats | St Francis Dune Thicket |
Description | Plants grow on coastal sand flats and mountain slopes in grassy fynbos. |
Threats |
Dairy farming and invasive Acacia cyclops have led to the degradation of the habitat of this taxon (Liltved and Johnson, 2012). The site is also densely infested with invasive alien wattles. This striking 'black' orchid is very popular with collectors; declines during the 1990s were noted due to the removal of individuals from the wild. |
Population |
This taxon is restricted to a single location, and not much is known about its population size and structure. It was last seen in 1993, and despite targeted searches, it has not been observed between 2003 and 2022. Little is known about its ecology, but fire is likely to be an essential part of its life history. Searches following the fire have not taken place, and ongoing monitoring, especially after the fire, is required to determine the current population size and status. The population is inferred to be declining due to the impact of invasive alien species.
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Population trend | Decreasing |
Assessment History |
Taxon assessed |
Status and Criteria |
Citation/Red List version | Disa lugens Bolus var. nigrescens (H.P.Linder) H.P.Linder | CR B1ab(iii,v)+2ab(iii,v) | Raimondo et al. (2009) | Disa lugens Bolus var. nigrescens (H.P.Linder) H.P.Linder | VU D2 | Victor (2002) | Herschelianthe lugens (Bolus) Rauschert var. nigrescens (H.P.Linder) N.C.Anthony | Endangered | Hilton-Taylor (1996) | |
Bibliography |
Hilton-Taylor, C. 1996. Red data list of southern African plants. Strelitzia 4. South African National Botanical Institute, Pretoria.
Johnson, S. and Bytebier, B. 2015. Orchids of South Africa: A field guide. Struik Nature, Cape Town.
Liltved, W.R. and Johnson, S.D. Unpublished. The Cape Orchids - Wild orchids of the Cape Floral Kingdom.
Linder, H.P. 1981. Taxonomic studies in the Disinae. VI. A revision of the genus Herschelia. Bothalia 13(3 & 4):365 - 388.
Linder, H.P. and Kurzweil, H. 1999. Orchids of southern Africa. A.A. Balkema, Rotterdam.
McMaster, C. 2007. Disa lugens: Eastern Cape orchird. Veld and Flora 93, 147-149.
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.
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Citation |
von Staden, L. & Liltved, W.R. 2023. Disa lugens Bolus var. nigrescens (H.P.Linder) H.P.Linder. National Assessment: Red List of South African Plants version . Accessed on 2025/02/18 |