Taxonomy
Scientific Name
Geissorhiza tulbaghensis F.Bolus
Higher Classification
Monocotyledons
Family
IRIDACEAE
National Status
Status and Criteria
Endangered B1ab(ii,iii,iv,v)+2ab(ii,iii,iv,v)
Assessment Date
2023/06/20
Assessor(s)
I. Ebrahim, D. Raimondo & R.C. Turner
Justification
This species has an extent of occurrence (EOO) of 909 km² and an area of occupancy (AOO) of 92 km². Between 15 and 20 small, severely fragmented subpopulations remain, mostly on road verges and in remnant patches of renosterveld. It has lost extensive habitat to wheat and vineyard expansion. It is suspected that there are fewer than 10 000 mature individuals extant. It continues to decline due to alien plant invasion, pesticide spraying and agricultural and urban expansion. It is therefore listed as Endangered under criterion B.
Distribution
Endemism
South African endemic
Provincial distribution
Western Cape
Range
It is endemic to Western Cape, South Africa, and is found from Porterville to Wellington.
Habitat and Ecology
Major system
Terrestrial
Major habitats
Swartland Shale Renosterveld, Breede Shale Renosterveld, Breede Shale Fynbos, Swartland Alluvium Fynbos, Breede Alluvium Fynbos
Description
It occurs on heavy, often stony clay soil in renosterveld.
Threats
This species has lost 71% of its habitat (calculated using landcover data in GIS). Agricultural transformation for wheat and vineyard farming has caused the loss of three subpopulations known from herbarium records. One subpopulation in the Tulbagh valley is likely to be ploughed in the near future (landowner pers. comm. with I. Ebrahim 2005). Half of the subpopulations are being impacted by alien grass invasion. There is also loss of pollinators due to pesticide spraying, two subpopulations are adjacent to farmlands and volunteers of the Custodians of Rare and Endangered Wildflowers (CREW) Programme have documented a decline in numbers of individuals due to pesticide spraying.
Population

The population has a decreasing trend and is known from between 15 and 20 subpopulations which are severely fragmented. One large subpopulation of 5000 individuals has been recorded, all other subpopulations are small with fewer that 250 mature individuals and many with fewer than 50.


Population trend
Decreasing
Assessment History
Taxon assessed
Status and Criteria
Citation/Red List version
Geissorhiza tulbaghensis F.BolusEN B1ab(ii,iii,iv,v)Raimondo et al. (2009)
Bibliography

Goldblatt, P. 1985. Systematics of the southern African genus Geissorhiza (Iridaceae-Ixioideae). Annals of the Missouri Botanical Garden 72(2):277-447.


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.


Goldblatt, P. and Manning, J.C. 2020. Iridaceae of southern Africa. Strelitzia 42. South African National Biodiversity 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.


Citation
Ebrahim, I., Raimondo, D. & Turner, R.C. 2023. Geissorhiza tulbaghensis F.Bolus. National Assessment: Red List of South African Plants version . Accessed on 2024/07/22

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Distribution map

© R. Koopman

© R. Koopman

© C. Paterson-Jones

© J.C. Manning

© J.C. Manning

© J.C. Manning

© J.C. Manning

© I. Ebrahim

© I. Ebrahim


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