Flame-lilies and Christmas Bells: The genera Gloriosa L. and Sandersonia Hook. (Colchicaceae: Colchiceae) in Southern Africa

Abstract

The genera Gloriosa L. and Sandersonia Hook. (Colchicaceae: Colchiceae) are revised for southern Africa, with full nomenclature, descriptions, distribution data and updated conservation assessments. All species are illustrated in colour. Both genera have a similar habit, with mostly cirrhose foliage and yellow (rarely greenish) to orange flowers nodding on slender extra-axillary pedicels, with a well-developed style longer than the branches. Despite their similar morphology, existing phylogenetic analyses indicate that they are not immediately related. Three species of Gloriosa are recognised from the region, distinguished by the shape and size of their flowers, and the orientation and relative length of the style. Gloriosa superba L., which is widespread through Africa and southeast Asia, is recognised by its relatively large flowers with recurved or reflexed tepals that are narrowed and ± clawed at the base, and a sharply flexed style. Capsule dehiscence is septicidal. Typical plants have a bicoloured red and yellow perianth but populations from the north-eastern parts of the subcontinent and also elsewhere in tropical Africa are predominantly plain yellow. The overlooked G. sect. Gloriola Chiov. is lectotypified against G. aurea Chiov., currently treated as a synonym of G. superba. A full nomenclator and synonymy of all names included in G. superba is provided for the first time, including the nomenclatural status of the names and their types. The two remaining species in the region share similar cup-shaped flowers with suberect, lanceolate tepals and erect style. The locally endemic G. rigidifolia (Bredell) J.C.Manning & Vinn. from the Waterberg in Limpopo, South Africa, has been confused with G. modesta (Hook.) J.C.Manning & Vinn. from eastern South Africa, Eswatini and Mozambique but it differs consistently from that species in its erect, mostly more floriferous habit and in its slightly smaller, greenish (vs mostly yellow or orange) flowers with slightly longer perianth tube and much longer style, and evidently also in its septicidal (vs loculicidal) capsule dehiscence. The two taxa constitute a species pair that differs from florally similar species from tropical Africa by the mostly whorled foliage and unusual nectaries with an auricle-like distal lobe on the lateral ridges. The monotypic genus Sandersonia is distinguished by its 3(5)-veined leaves, urceolate or lantern-shaped flowers with small, pouched or shortly spurred nectary, and verrucose seeds. The single species S. aurantiaca Hook. is endemic to temperate grasslands in South Africa and adjacent Eswatini.