Plant story

Dioscorea sp.

Ex situ conservation of a newly discovered species of Dioscoreaceae in Mpumalanga Province, Republic of South Africa

During 1999, a sample of what was thought to be a Dioscorea species was brought to a local, community-driven, medicinal plant nursery by an old traditional healer. According to this man, the plant has been extensively collected for it's medicinal properties. After the plant was brought to the attention of Gerhard Strydom of Mpumalanga Parks Board (MPB), it was taken to the Lowveld Botanical Gardens in Nelspruit where Johan Hurter confirmed that it was an undescribed Dioscorea species.

A subsequent visit to the plant locality in June 2000, by Gerhard Strydom and Johan Hurter revealed just how scarce a find this plant was. Based on information from local traditional healers, and after extensive exploration of the area, we were convinced that this was indeed the only population in the area. To make matters worse, a quick survey revealed that the population consisted of 107 plants, of which only around 40 were mature. In addition, the species is dioecious, and with only 9 plants being female, it became increasingly clear that the survival of this species was in doubt.

Although the plant is being cultivated in the local community nursery and in the National Botanical Institute’s botanical garden in Nelspruit, further concern for the overexploitation of the plants culminated in the involvement of the Millennium Seed Bank Project (MSBP). In April 2001, Erich van Wyk and the South African MSBP team collected approximately 3000 seeds by sampling small amounts from all the female plants bearing seed at the time. The collection is currently being stored long term at the Millennium Seed Bank. While collecting the seed, all relevant demographic data was collected about the population, ecology and site. Apart from serving as a back-up collection in case of the worst, the collection will also be used to develop a propagation protocol. During this process any problems with dormancy or seed behaviour will be studied by the Research Section at the MSB. If necessary, over time, the seed collection could even be bulked up by cultivating the species, and collecting more seed from the cultivated plants. Seed viability can be determined from the seed harvested in nature and from cultivated plants, giving insight into conservation problems that might arise in the wild population.

All the data accumulated will be combined in a Species Dossier and distributed to the MPB and all relevant Botanical Gardens. These data will enable the MSPB to make informed decisions, and develop tailored conservation strategies for the species. In addition, the germplasm is available for conservation activities (e.g. reintroduction, supplementation etc.) as and when these are appropriate.

Currently the conservation status of the newly described Dioscorea sp. is being assessed according to the latest IUCN criteria. This taxon must obtain priority conservation and legal status, to ensure the survival of this unique species.

Authors:

Erich van Wyk
National Co-ordinator: Millennium Seed Bank Project, Republic of South Africa.
SANBI, Pretoria.

Johan Hurter
Lowveld National Botanical Garden
SANBI, Melspruit, Mpumalanga, Republic of South Africa.