During the collection of specimens for the Southern Cape Herbarium, George, Western Cape, South Africa, a number of plants of an unusual scandent Crassula species, subsequently identified as C. fragilis (Schonl. 1929), were found along the dunes west of Mossel Bay. TÖlken (1985) had previously placed this taxon in the synonymy of C. pubescens Thunb. and in particular as a synonym of C. p. subsp. pubescens. Apart from specimens examined, plants were grown in cultivation and compared to that of a range of forms attributed to C. p. subsp. pubescens. Not only does C. fragilis differ from C. pubescens in habit, growth form and floral morphology but it is endemic to the coastal dunes mostly in association with limestone. In contrast C. p. subsp. pubescens has wide habitat tolerances centred around rocky outcrops and rocky and stony soils mostly derived from shale and sandstone. Both taxa belong to the Section Globulea with large terminal appendages on the petals but these differ between the two taxa. These and other characteristics are considered sufficient to justify the re-instatement of C. fragilis to species status.
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23 June 2021
Is Crassula fragilis Schonl. a Valid Taxon or Synonymous with C. pubescens Thunb. subsp. Pubescens?
Niels HG Jacobsen
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Cactus and Succulent Journal
Vol. 93 • No. 2
Summer 2021
Vol. 93 • No. 2
Summer 2021