Taxonomy
Scientific Name
Dioscorea strydomiana Wilkin
Higher Classification
Monocotyledons
Family
DIOSCOREACEAE
National Status
Status and Criteria
Critically Endangered B1b(iii,v)+2b(iii,v); C1+2a(ii)
Assessment Date
2022/05/18
Assessor(s)
L. von Staden, J.E. Victor, D. Raimondo, P.J.H. Hurter & N.N. Mhlongo
Justification
This species is a highly restricted endemic known from one location with fewer than 250 mature individuals. It has an extent of occurrence (EOO) and an area of occupancy (AOO) of less than 10 km². The tubers of this species are used as medicine by the Ebutsini tribe, on whose tribal land the only known subpopulation occurs. Medicinal harvesting is causing a continuing decline in the number of mature individuals. It appears to be a very slow growing species (generation length estimated to be 50 years). There has been at least a 25% decline in the number of mature individuals in the past 150 years as a result of medicinal harvesting. Cattle farming, firewood collection, burning and porcupine damage further threaten this species. It therefore qualifies as Critically Endangered under criteria B and C.
Distribution
Endemism
South African endemic
Provincial distribution
Mpumalanga
Range
This species is endemic to the Mpumalanga Province, where it occurs near Oshoek.
Habitat and Ecology
Major system
Terrestrial
Major habitats
KaNgwane Montane Grassland
Description
Plants grow in open woodland on steep, rocky, southeast to south southeast-facing slopes on dolerite with quartzite intrusions, at altitudes of 1100 m.
Threats
The main threat to this species is harvesting tubers for traditional medicine, which monitoring has shown to be unsustainable as the population is very small and the plants are extremely slow growing. Additionally, the species faces potential threats from collection for horticultural purposes, driven by its appealing pachycaul growth form. However, its slow growth makes cultivation challenging, potentially increasing pressure on the wild population to meet commercial demand. There is also a looming threat from mining, as a prospecting application for the property was recently submitted. The persistence of this species is further challenged by factors such as porcupine damage, burning, cattle farming, and firewood collection.
Population

The population of about 250 plants has been monitored annually since 2007. Harvesting damage has been noted in 91% of tagged individuals, and 32% of monitored individuals have died due to overharvesting since 2008.


Population trend
Decreasing
Notes
This species has great horticultural potential. Conservation measures by means of propagation in cultivation have been put in place (Hurter 2003).
Assessment History
Taxon assessed
Status and Criteria
Citation/Red List version
Dioscorea sp. nov. (Hurter 106 GLOW, PRU)CR B1ab(v)+2ab(v); C1Raimondo et al. (2009)
Bibliography

Hurter, J. 2003. A new pachycaul Dioscorea species from Mpumalanga Province, South Africa and its conservation. Aloe 40(3&4):73-75.


Hurter, P.J.H. and van Wyk, A.E. 2004. A new species of Acacia (Mimosoideae) from Mpumalanga, South Africa: Acacia ebutsiniorum. Bothalia 34(1):42-44.


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.


Wilkin, P., Burrows, J., Burrows, S., Muasya, A. and Van Wyk, E. 2010. A critically endangered new species of yam (Dioscorea strydomiana Wilkin, Dioscoreaceae) from Mpumalanga, South Africa. Kew Bulletin 65(3):421-433.


Citation
von Staden, L., Victor, J.E., Raimondo, D., Hurter, P.J.H. & Mhlongo, N.N. 2022. Dioscorea strydomiana Wilkin. National Assessment: Red List of South African Plants version . Accessed on 2025/02/18

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Distribution map

© M. Lötter

© M. Lötter

© M. Lötter

© M. Lötter

© Mpumalanga Parks and Tourism Agency (M.T.P.A.)

© M. Lötter

© M. Lötter

© M. Lötter

© M. Lötter


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