on the outside. They are subtended by a swelling that contains a cavity that contains nectar. When the swelling is touched, the anther explosively swings up, releasing the pollen through the slits. The superior ovary in the center of the flower consists of three merged carpels, that together protect three cavities within which are one to four anatropous ovules each of which is covered by a single layer. The upright style tapers towards the top and carries a small globe-shaped stigma or expands towards the top into an inverted cone-shaped stigma, covered in small grains. The smooth, cartilaginous, dehiscent fruit opens with three valves. The small, dark reddish brown seeds are ellipsoid in shape either with a smoothed netted structure or angular with three sutures and with prominent warts or a honeycomb-like structure. Both species are diploids having six sets of homologue chromosomes (2n=12). Differences between the species R. dentata can be distinguished by its larger habit of up to 2 m, the line-shaped lobes along its leaves and the umbel-like inflorescences, whereas R. gorgonias is smaller, up to 1⅓ m, has entire leaves and spike-like inflorescences. Taxonomy Carl Linnaeus described Roridula in 1764. The name Roridula derives from roridus, a Latin word meaning “dewy”, which refers to the fine drops of liquid on the tentacles that give the leaves a dewy appearance. Over time, different botanists have held different views on the affinities of the genus Roridula. Jules Émile Planchon thought it should be assigned to the Ochnaceae in 1848. George Bentham and Joseph Dalton Hooker, two of the nineteenth century's most influential British botanists however, included it in 1867 in the Droseraceae. In 1912, Johannes Gottfried Hallier regarded Roridula as a specialized member of the Clethraceae. Hutchinson in 1959, and Arthur Cronquist in 1981 included it in the Byblidaceae. Current insights in the relationships of the Roridulaceae, based on a 2015 DNA-analysis, are summarized in the following tree. Distribution, habitat and ecology The genus Roridula is endemic to parts of the mountains in the west and southwest of the Western Cape province of South Africa. R. dentata can be found in the mountains of Tulbagh, Clanwilliam and Ceres. R. gorgonias occurs between Somerset West and Swellendam. Both species grow on acidic and nutrient-poor, sandy soils, in locations that are relatively moist, at altitudes of 900–1200 m (2950–3950 ft) for R. dentata and 150–925 m (500–3000 ft) for R.