Strumaria bidentata

Scientific Name
Strumaria bidentata Schinz
Higher Classification
National Status
Status and Criteria
Critically Endangered B1ab(iii,v)
Assessment Date
P.C.V. Van Wyk, D.A. Snijman & D. Raimondo
A range-restricted species in South Africa (national EOO <70 km²), known from one location and declining due to ongoing habitat loss, degradation and trampling due to overgrazing and mining.
Not endemic to South Africa
Provincial distribution
Northern Cape
Richtersveld, lower Gariep Valley inland of Alexander Bay, as well as southern Namibia (Sperrgebiet).
Habitat and Ecology
Major system
Major habitats
Western Gariep Lowland Desert, Western Gariep Plains Desert
Gravel plains and sandy flats.
This species is threatened by severe, ongoing habitat loss and degradation due to mining and overgrazing. It has also lost some habitat to irrigated crop cultivation on the banks of the Orange River in the past. This species' range within South Africa is entirely within one large communally owned rangeland, and the whole population is subjected to severe overgrazing and trampling, particularly as a result of a significant increase in stocking rates over the past 10 years, and rapid, severe population declines have been observed.

This species is localized to a small area, where it occurs in small, scattered subpopulations of only a few individuals, typically fewer than 10 plants. Prior to the introduction of large herds of livestock in 2006, subpopulations were significantly larger. It is estimated that one subpopulation south of Kortdoringberg has declined by more than 90% in 10 years - previously there were well over 1000 plants, but now only a handful of plants remain (P.C.V. van Wyk pers. comm. 2014). This species also occurs in southern Namibia, but is also rare and poorly known there. Due to extremely limited dispersal ability of Strumaria species, it is unlikely that there is significant dispersal between the South African and Namibian population (D. Snijman pers. comm. 2015).

Population trend
Assessment History
Taxon assessed
Status and Criteria
Citation/Red List version
Strumaria bidentata SchinzCR B1ab(iii,v)2015.1
Strumaria bidentata SchinzEN B1ab(iii,v)Raimondo et al. (2009)
Strumaria bidentata SchinzLower Risk - Near Threatened Victor (2002)
Strumaria bidentata SchinzIndeterminate Hilton-Taylor (1996)

Hilton-Taylor, C. 1996. Red data list of southern African plants. Strelitzia 4. South African National Botanical Institute, Pretoria.

Hilton-Taylor, C. Unpublished. Succulent Karoo Red Data List (version 1997 - in preparation). SANBI.

Müller-Doblies, D. and Müller-Doblies, U. 1985. De Liliifloris notulae 2: De taxonomia subtribus Strumariinae (Amaryllidaceae). Botanische Jahrbücher für Systematik 107:17-47.

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.

Snijman, D.A. 1992. Notes on the Strumariinae (Amaryllidaceae : Amaryllideae): six new taxa in Strumaria and Hessea from the central and northwestern Cape, South Africa, and southern Namibia. Bothalia 22(1):1-11.

Snijman, D.A. 1994. Systematics of Hessea, Strumaria and Carpolyza (Amaryllideae: Amaryllidaceae). Contributions from the Bolus Herbarium 16:1-162.

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.

Van Wyk, P.C.V., Snijman, D.A. & Raimondo, D. 2015. Strumaria bidentata Schinz. National Assessment: Red List of South African Plants version 2017.1. Accessed on 2018/06/21

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Distribution map

© C. Paterson-Jones

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