Taxonomy
Scientific Name
Diosma aristata I.Williams
Higher Classification
Dicotyledons
Family
RUTACEAE
National Status
Status and Criteria
Critically Endangered C2a(ii)
Assessment Date
2012/07/10
Assessor(s)
A.L. Schutte-Vlok & V. Zikishe
Justification
The only known subpopulation of Diosma aristata is now fragmented due to urban expansion and coastal development, and currently consist of less than 250 mature individuals. Plants remain at two locations, about 140 in a small municipal reserve where they continue to decline due to ongoing habitat degradation, and between 50 and 100 plants remain within a private golf estate in another small fragment near the coast, where plants are threatened by habitat degradation due to alien plant invasion and a lack of fire.
Distribution
Endemism
South African endemic
Provincial distribution
Western Cape
Range
Mossel Bay.
Habitat and Ecology
Major system
Terrestrial
Major habitats
Hartenbos Strandveld
Description
Deep sandy soil or amongst rocks in coastal fynbos.
Threats
A large part of this species' population has already been lost to coastal development. Currently the habitat of remaining plants are protected in local reserves, but are not efficiently managed to protect this species. Alien plants have been cleared, but follow up clearing and ongoing management is needed to prevent reinvasion, and the reserve is frequently used as a dumping site. Further south, the habitat of a small clump of plants cut off from the rest of the subpopulation by the golf estate development is not being managed, and fire is excluded from this site due to the risk to private property. This species is a reseeder dependent on fire.
Population

Diosma aristata is known from a single subpopulation to the west of Mossel Bay, where the species originally extended as a single large subpopulation over an area from the coast to about 2 km inland. This subpopulation has however been dissected and fragmented by a residential golf estate development, and fewer than 250 plants remain in two patches. In both these areas, plants continue to decline due to ongoing habitat degradation.


Population trend
Decreasing
Assessment History
Taxon assessed
Status and Criteria
Citation/Red List version
Diosma aristata I.WilliamsCR B1ab(iii,v)+2ab(iii,v); C2a(ii)Raimondo et al. (2009)
Diosma aristata I.WilliamsCR A1aceB1B2abceC2bVictor (2002)
Diosma aristata I.WilliamsEndangered Hilton-Taylor (1996)
Diosma aristata I.WilliamsEndangered Hall et al. (1980)
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.


Hall, A.V., De Winter, M., De Winter, B. and Van Oosterhout, S.A.M. 1980. Threatened plants of southern Africa. South African National Scienctific Programmes Report 45. CSIR, Pretoria.


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.


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.


Williams, I. 1974. Studies in the genera of the Diosmeae (Rutaceae): 4. Journal of South African Botany 40:275-290.


Williams, I. 1975. Studies in the genera of the Diosmeae (Rutaceae): 5. Journal of South African Botany 41:167-186.


Williams, I. 1982. Studies in the genera of the Diosmeae (Rutaceae): 14. A review of the genus Diosma L. Journal of South African Botany 48(3):329-407.


Citation
Schutte-Vlok, A.L. & Zikishe, V. 2012. Diosma aristata I.Williams. National Assessment: Red List of South African Plants version 2020.1. Accessed on 2024/02/24

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Distribution map

© A.L. Schutte-Vlok

© A.L. Schutte-Vlok

© A.L. Schutte-Vlok

© Outramps


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