|
Scientific Name | Geissorhiza lewisiae R.C.Foster |
Higher Classification | Monocotyledons |
Family | IRIDACEAE |
National Status |
Status and Criteria | Near Threatened B1ab(i,ii,iii,iv,v)+2ab(i,ii,iii,iv,v) |
Assessment Date | 2023/06/06 |
Assessor(s) | L. von Staden & T. Patel |
Justification | This species has an extent of occurrence (EOO) of 11 073 km² and an area of occupancy (AOO) of 92 km². Between 13 and 15 extant locations continue to decline due to ongoing habitat loss to crop cultivation, urban development and quarrying. It is therefore listed as Near Threatened under criterion B. |
Distribution |
Endemism | South African endemic |
Provincial distribution | Western Cape |
Range | It is endemic to the Western Cape province of South Africa where it is largely restricted to the Saldanha District. It extends from Steenberg Cove to the Posberg Peninsula. It is also local in the upper Olifants River Valley and also occurs between Stellenbosch and Malmesbury. |
Habitat and Ecology |
Major system | Terrestrial |
Major habitats | Saldanha Flats Strandveld, Saldanha Granite Strandveld, Citrusdal Shale Renosterveld |
Description | It occurs on granite outcrops, limestone pavements and calcrete soils. |
Threats |
| This species has lost 51% of its habitat (calculated using landcover data in GIS) to crop cultivation, urban development and quarrying of granite rocks. |
Population |
Most of the extant subpopulations occur on the Vredenburg Peninsula. There are only a few records from the Olifants River Valley where much of its habitat there has been transformed for crop cultivation. Population data for this species is not available, but herbarium labels indicate that it can be locally common. Monitoring via the iNaturalist platform between 2017 and 2023 has extended the known range of this species and it is now confirmed to also occur between Stellenbosch and Malmesbury. It has a declining population trend.
|
Population trend | Decreasing |
Assessment History |
Taxon assessed |
Status and Criteria |
Citation/Red List version | | Geissorhiza lewisiae R.C.Foster | VU B1ab(i,ii,iii,iv,v)+2ab(i,ii,iii,iv,v) | 2011.1 | | Geissorhiza lewisiae R.C.Foster | Indeterminate | Hall et al. (1980) | |
Bibliography |
Goldblatt, P. and Manning, J.C. 2020. Iridaceae of southern Africa. Strelitzia 42. South African National Biodiversity Institute, Pretoria.
Goldblatt, P., Manning, J.C. and Nänni, I. 2009. New species of Geissorhiza (Iridaceae:Crocoideae) from the southern African winter rainfall zone, range extensions, taxonomic changes, and notes on pollen morphology. Bothalia 39(2):123-152.
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.
|
Citation |
| von Staden, L. & Patel, T. 2023. Geissorhiza lewisiae R.C.Foster. National Assessment: Red List of South African Plants version . Accessed on 2024/12/07 |
Comment on this assessment
