"Conservationists heaved a collective sigh of relief when the latest census in a West Coast nature reserve revealed the presence of an increased, but still very small, number of one of southern Africa's rarest plants.
... Disa barbata, a white-flowering orchid with a frilly lip that is known in Afrikaans as Ouman met sy baard (old man with his beard). Over the past fortnight, Stellenbosch University researchers and CapeNature officials conducted a census in which they found 55 specimens of this highly endangered plant. Just 32 plants were counted after last year's very dry winter. The alarm about the plant's precarious status was sounded in 2001 by East African botanist ... Benny Bytebier, who was working with Stellenbosch University biochemistry professor Dirk Bellstedt to analyse the evolutionary path of the entire Disa genus, a group of orchids unique to Africa that comprises 180 species. Collecting fresh material for his research, he was concerned when a day-long search in the reserve turned up just eight disas. The reserve, managed by CapeNature, is the only known location of this species that once also occurred on the Cape Flats around Kenilworth, Rondebosch and Pinelands. All these habitats have disappeared under the sprawling concrete mass of the city. The disa, last recorded in the Cape Town area in 1950, can only be spotted during a two-week period around the end of October when it is in flower. For the rest of the year, its tubers remain underground and undetectable, blending in with the Cape reeds (restios) among which they grow. Despite the use of GPS (geographical positioning system) location markers, many of last year's 32 plants were not seen during this year's census. It therefore appears that many of these disas lie dormant for several years before they decide to flower again, and researchers are now trying to understand why this happens. In its natural habitat, this particular disa is pollinated by a carpenter bee, Xylocopa rufitarsis. "These bees depend on dead wood for nesting sites, and this means that fire, an integral part of the fynbos ecosystem, will have to be managed carefully in future," Bytebier said. "Unfortunately, the pollination success is generally low. Only 15% of the flowers observed in 2002 reached the stage of a mature seed pod." According to reserve manager Louise de Roubaix, the conservation area is extremely sensitive, with more than 780 plant species occurring in less than 7 000 hectares. It is renowned especially for the variety and beauty of its many bulb species, and Disa barbata is one of 42 known endangered plant species found there. .... To boost numbers of the disa, Stellenbosch University scientists are propagating plants artificially through seed germination in tissue culture. Last year, the scientists were able to report that the orchid's seeds had successfully germinated. Disas have big horticultural appeal, so the team plans to sell some of the artificially propagated plants to interested disa-growers. They hope this will prevent poaching of the few remaining wild specimens in the reserve and allow them to recover some of their costs. Their work and further conservation efforts at the reserve are supported financially by the Endangered Species Fund of the Chicago Zoological Society and the Chicago Board of Trade. Artificially propagated disas could be reintroduced to the reserve, though this would be a "last resort". Better management to improve the disa population in its natural habitat is considered to be the sounder conservation practice." source and complete news item : http://www.capeargus.co.za/index.php?fSectionId=49&fArticleId=2987401 ********** Regards, Viateur _______________________________________________ the OrchidGuide Digest (OGD) [email protected] http://orchidguide.com/mailman/listinfo/orchids_orchidguide.com
