Carnivorous plants stand out as one of the most unusual of all adaptations. The ability to consume required nutrients through the enzymatic degradation of insects has fascinated anyone who has come across a Venus fly trap (Dionaea muscipula) or pitcher plant (Saracina sp. or Nepanthese sp.). Although less obvious than some of their carnivorous cousins, sundew (Drosera sp.) are equally interesting and can be found in the wild of every continent (aside from Antarctica).
Sundew, or Drosera, gained its name because of the “dew like” mucilage secretion that form drops at the end of the leaves of the plants in the genus. Droser are most closely related to Dionaea (Venus fly trap) of all the carnivorous plants. The center of diversity is found in Australia with close to 50% of the 194 known species to be found there. Drosera has a preference for a boggy habitat and can be found in seeps, swamps and other continuously saturated lands. Their carnivorous adaptation is the growth of a gland bearing stalk that secretes mucilage that attracts small insects. Once insects are trapped on this “fly paper” some species will wraps their leaves around their pray before releasing esterase, peroxidsase, phosphatase and protease enzymes (Karnivoren, biologie und kutur, W. Barthlott et al. 2004) that digest and degrade the insect bodies, thus harvesting essential plant nutrients.
South Africa is known to have a number of Drosera species including Drosera regia, one of the most spectacular within the genus. Drosera regia is aptly dubbed the King Sundew and has not come to receive such a commanding common name for nothing. Aside from its insectivorous appetite, this species is known for its unusually large foliage. With single leaf blades able to grow upwards of 70 cm (27 inches) it is undoubtedly regal in the hierarchy of the Droseras. Because of this strange and alarmingly large growth, this species has become a fascination in the botanical community among collectors and carnivorous plant aficionados.
Drosera regia is known to occur in an extremely small natural range. It is found only in one river valley on the Bains Kloof Pass in South Africa. Most accounts will note that even within this valley, only two known populations can be found and exhibit small morphological differences. In talking with various local botanists, they report anywhere from two to four populations that have been found or stumbled upon.
There are conflicting view points on the conservation status of Drosera regia. A challenge, oftentimes faced by plant taxonomists or conservationists, is the attempt to place artificial frameworks onto biological organisms. The challenge arises from attempts to strictly describe organisms that are typified by morphology, phenotype and reproductive plasticity. In the South Africa Red List of Threatened Species, this D. regia is currently listed as “Rare” although a 2009 assessment described it as the lowest conservation status of “Least Concern.” Others will argue that this species should be considered “Vulnerable” or “Endangered” (at risk of extinction) due to its extremely small distribution, over-harvesting from collectors, and threats from encroaching grasses and shrub species. This shows some of the practical challenges that face plant conservation efforts. With South Africa’s vast flora and countless species that face similar threats, only the most rare or most threatened species tend to receive conservation focus.
Grown in cultivation, Drosera regia can be found in botanical gardens and with specialist carnivorous plant collectors. Still a target for unethical plant collectors, this species is at risk by a combination of both habitat loss and over-exploitation.
Stellenbosch Botanical Garden’s first curator Hans Herre came out to Baines Kloof and was able to re-discover the population. Herre was dropped of into the remote mountain region and was left with 4 days to explore the mountains, rivers and tributaries in search of the reportedly robust species. After days of searching, Herre finally located a living population on the fourth day of his excursion. Examining historical records, it has been observed that Drosera regia once grew in Stellenbosch Botanical Garden’s collections, undoubtedly a result of Herre’s collecting in the area.
Because of the confusing conservation status of Drosera regia, little effort has been placed on the preservation of this species. With Stellenbosch Botanical Garden’s historical cultivation of the species and because of the lack of protective efforts for Drosera regia, it has become a priority for their growing conservation program. A series of steps was planned out to secure plants and develop a management plan. The first is field exploration to find the viable populations and identify their exact locations. Congruently Drosera regia from garden provenance are being secured to explore the horticultural specifications of growing this species in cultivation. In coming years, this will be followed up by repeat visits to the known localities, ethical collecting of seeds from each population, and cultivation within the living collections. This approach will allow for the Garden to focus on monitoring the populations in the wild (in-situ) as well as preserve their germplasm in the Garden (ex-situ).
A trip out to Baines Kloof was planned at the end of September in attempts to find populations of Drosera regia. After a full day of hiking through mountainous terrain we were lucky enough to location one population just prior to having to turn back before dark. Martin Smit Stellenbosch BG Curators was the first in the party to location the Sundew glimmering in the late day glow. With this find he stands as the second of four Stellenbosch BG curators to locate and explore Drosera regia in this locality. With a legacy of conservation efforts this garden is making continuing contributions to plant preservation and keeping with gardens principles, which have sustained it for over ninety years.
Below are pictures from the exploration of Baines Kloof