Dioscorea strydomiana Wilkin

Taxonomy
Scientific Name
Dioscorea strydomiana Wilkin
Higher Classification
Monocotyledons
Family
DIOSCOREACEAE
National Status
Status and Criteria
CR B1ab(v)+2ab(v); C1
Assessment Date
2011/09/22
Assessor(s)
L. von Staden, J.E. Victor, D. Raimondo & P.J.H. Hurter
Justification
Recently discovered, known from one location and fewer than 250 mature individuals. 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 of 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.
Distribution
Endemism
South African endemic
Provincial distribution
Mpumalanga
Range
Oshoek.
Habitat and Ecology
Major system
Terrestrial
Major habitats
Savanna
Description
Exposed, open grassland, in serpentine soils on steep, southeast-facing slopes, 1100 m.
Threats
The main threat to this species is harvesting of tubers for traditional medicine, which monitoring has shown to be unsustainable as the population is very small and plants are extremely slow growing. The species is also potentially threatened by collection for horticultural purposes, as it has an attractive pachycaul growth form, but being very slow growing it is likely to be difficult to establish in cultivation, which may put pressure on the wild population to meet commercial demand. Mining is another potential future threat - a prospecting application for the property was recently submitted.
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
Date
Taxon assessed
Status and Criteria
Citation/Red List version
2009Dioscorea 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. 2011. Dioscorea strydomiana Wilkin. National Assessment: Red List of South African Plants version 2013.1. Accessed on 2014/04/16

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Distribution map

(c) M. Lötter

(c) M. Lötter

(c) M. Lötter

(c) M. Lötter

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


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