|
Scientific Name | Cucumis humifructus Stent |
Higher Classification | Dicotyledons |
Family | CUCURBITACEAE |
National Status |
Status and Criteria | Vulnerable B1ab(ii,v) |
Assessment Date | 2006/12/21 |
Assessor(s) | J.E. Victor & M.F. Pfab |
Justification | A range-restricted species within South Africa (EOO 8300 km²), but widespread elsewhere in Africa. Known from 6-10 old herbarium records, none of which are from reserves. It is entirely dependent on aardvarks for dispersal and recruitment, and is probably declining due to local extinctions of aardvarks outside reserves in South Africa. Historical locations within Gauteng cannot be relocated and it is presumed to be locally extinct. |
Distribution |
Endemism | Not endemic to South Africa |
Provincial distribution | Limpopo |
Range | Eastern and southern tropical Africa, in Gauteng and Limpopo and from Kenya to northern Namibia. |
Habitat and Ecology |
Major system | Terrestrial |
Major habitats | Central Sandy Bushveld |
Description | Woodland and grassland, deep sand, 1350-1500 m. |
Threats |
| The dispersal and propagation of this species is entirely dependent on a symbiotic relationship with the aardvark. Should aardvarks decline, this species will rapidly disappear from areas where aardvarks have become locally extinct.
Aardvarks are not currently considered threatened with extinction (Lindsey et al. 2006) as populations within reserves are stable, and many new private game and hunting reserves are being established, leading to populations recovering in areas where it was formerly declining (M. Keith pers. comm.). However, outside of reserves aardvarks are still threatened. They are hunted for medicinal use (parts have been found in the Faraday market in Johannesburg) as well as bush meat (M. Keith and T. Lehmann pers. comm.).
Considering that no records of Cucumis humifructus are known from within reserves, local extinctions of aardvarks are highly likely to be a threat across the range of this species. The distribution within South Africa is known from very old herbarium specimens, and no collections have been made in recent years. Searches at historical localities within Gauteng have been unsuccessful. These subpopulations are considered locally extinct, mainly due to a combination of urbanisation and local extinctions of aardvarks.
Some subpopulations may also have been destroyed by cultivation in the past. Meeuse (1955) reports that fruits arrived at the national herbarium for identification usually after ploughing has turned them up. However, the deep sandy soil where this species grows is only marginally suitable for agriculture as it is very nutrient poor. Agriculture is therefore unlikely to have been a serious past or current ongoing threat (P. Winter pers. comm.). |
Population |
Population trend | Decreasing |
Notes |
| Cucumis humifructus is one of the most remarkable species in the cucumber family, being the only one that produces its fruits underground. Field studies have revealed that C. humifructus is entirely dependent on aardvark for the dispersal and germination of seeds. The aardvark is the only animal known to dig up and consume the fruits of C. humifructus, and plants are generally only found around aardvark burrows. Aardvarks also have the peculiar habit of burying their dung, thereby providing a welcome planting and manuring service to the seeds (Meeuse 1955; Hollman et al. 1995). It may be that the plants require the extra nutrients provided by aardvark dung, since the sandy soils where this species grows are generally very nutrient poor (P. Winter pers. comm.).
The scarcity of records of this species may be because it is an annual, only growing for 3-4 months during the year. The rest of the time only the underground fruits remain (Hollman et al. 1995). Meeuse (1955) also speculated that it is probably an overlooked, rather than a rare, species, and expressed the expectation that it would probably also be found in the Northern Cape and adjacent areas in the North West Province (for example Gordonia, Kenhardt, Kuruman, Vryburg and Mafeking), Botswana and elsewhere in Limpopo and Mpumalanga (Polokwane, Soutpansberg, Potgietersrus and Lydenburg districts). However, to date this species is still only known from a few collections from the Waterberg and northern Gauteng. |
Assessment History |
Taxon assessed |
Status and Criteria |
Citation/Red List version | | Cucumis humifructus Stent | VU B1ab(ii,v) | Raimondo et al. (2009) | | Cucumis humifructus Stent | EN B1ab(i,ii,iii,iv)+2ab(i,ii,iii,iv) | Pfab and Victor (2002) | | Cucumis humifructus Stent | EN B1B2abcde | Victor (2002) | | Cucumis humifructus Stent | Insufficiently Known | Hilton-Taylor (1996) | |
Bibliography |
Hilton-Taylor, C. 1996. Red data list of southern African plants. Strelitzia 4. South African National Botanical Institute, Pretoria.
Meeuse, A. 1955. The aardvark cucumber: more information required about this rare plant. Farming in South Africa(June):301-304.
Meeuse, A.D.J. 1962. The Cucurbitaceae of southern Africa. Bothalia 8(1):1-112.
Pfab, M.F. and Victor, J.E. 2002. Threatened plants of Gauteng, South Africa. South African Journal of Botany 68:370-375.
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.
|
Citation |
| Victor, J.E. & Pfab, M.F. 2006. Cucumis humifructus Stent. National Assessment: Red List of South African Plants version . Accessed on 2025/05/12 |
Comment on this assessment
