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Scientific Name | Isoetes welwitschii A.Braun |
Higher Classification | Ferns |
Family | ISOETACEAE |
Synonyms | Calamaria natalensis (Baker) Kuntze, Calamaria welwitschii (A.Braun) Kuntze, Isoetes natalensis Baker |
National Status |
Status and Criteria | Least Concern |
Assessment Date | 2011/11/30 |
Assessor(s) | J.E. Burrows & L. von Staden |
Justification | Widespread but extremely rare and poorly known in South Africa. Although this species could not be found for many years in KwaZulu-Natal, it is suspected to be overlooked, as plants are cryptic and difficult to distinguish from young grass shoots. It is possibly threatened by wetland degradation in KwaZulu-Natal, but subpopulations in Mpumalanga are not threatened. |
Distribution |
Endemism | Not endemic to South Africa |
Provincial distribution | KwaZulu-Natal, Limpopo, Mpumalanga |
Range | Extremely rare and scattered distribution in South Africa from Polokwane to the KwaZulu-Natal Drakensberg. Extending to central and tropical Africa and Madagascar. |
Habitat and Ecology |
Major system | Freshwater |
Major habitats | Grassland, Savanna |
Description | Seasonally wet seepages in montane grassland, 1 400-1 600 m. |
Threats |
| Potentially threatened by habitat degradation as a result of overgrazing in KwaZulu-Natal. However, the life cycle of at least one other species of Isoetes (I. wormaldii) is known to be aided by trampling by cattle. I. welwitschii is however too poorly known to determine its response to disturbance. Subpopulations in Mpumalanga are not threatened, but the species is extremely rare in the province (Burrows 1990). |
Population |
Isoetes welwitschii is extremely rare in Mpumalanga (Burrows 1990). It was not collected for a very long time in KwaZulu-Natal (Burrows 1990), but recollected at a historical locality near Estcourt in 2002 (J.P. Roux pers. comm.). The occurrence of this species in Limpopo Province is uncertain, as plants collected near Polokwane may also be I. aequinoctialis (J.E. Burrows pers. comm.). The genus Isoetes is taxonomically problematic and in need of revision (J.P. Roux pers. comm.), and species are very difficult to identify with good confidence, so that at this stage it is not possible to accurately determine the distribution range of I. welwitschii (J.E. Burrows pers. comm.). Isoetes species are also easily overlooked, and may be more common than collections indicate. It is fairly common in Angola (J.P. Roux pers. comm.).
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Population trend | Stable |
Notes |
| Isoetes welwitschii in South Africa was previously treated as a separate species, Isoetes natalensis (Pfeiffer 1922), but later synonymised with the more widespread I. welwitschii which was first described from Angola (Burrows 1990). |
Assessment History |
Taxon assessed |
Status and Criteria |
Citation/Red List version | | Isoetes welwitschii A.Braun | NT D2 | 2011.1 | | Isoetes welwitschii A.Braun ex Kuhn | NT D2 | Raimondo et al. (2009) | |
Bibliography |
Burrows, J.E. 1990. Southern African ferns and fern allies. Frandsen Publishers, Sandton.
Cook, C.D.K. 2004. Aquatic and wetland plants of southern Africa. Backhuys Publishers, Leiden, The Netherlands.
Crouch, N.R., Klopper, R.R., Burrows, J.E. and Burrows, S.M. 2011. Ferns of southern Africa: A comprehensive guide. Struik Nature, Cape Town.
Pfeiffer, N.E. 1922. Monograph of the Isoetaceae. Annals of the Missouri Botanical Garden 9:79-232.
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.
Sieben, E.J.J. 2009. The status and distribution of vascular plants (Magnoliophyta, Lycophyta, Pteridophyta). In: W.R.T. Darwall, K.G. Smith, D. Tweddle and P. Skelton (eds.), The status and distribution of freshwater biodiversity in southern Africa (pp. 83-98), IUCN and SAIAB, Gland, Switzerland and Grahamstown, South Africa.
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Citation |
| Burrows, J.E. & von Staden, L. 2011. Isoetes welwitschii A.Braun. National Assessment: Red List of South African Plants version . Accessed on 2025/04/14 |
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