Character variation and a cladistic analysis of the genus Lachenalia Jacq.f. ex Murray (Hyacinthaceae)

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Abstract

The horticulturally important and botanically diverse genus Lachenalia Jacq. f. ex Murray is endemic to southern Africa, and is the largest member (115 species) of the Hyacinthaceae. The genus is morphologically and cytologically variable. Species delimitation is usually unambiguous but in some instances there is gradation between species. Other species display extensive variation which has led to considerable taxonomic confusion. The close taxonomic relationship with the small endemic, sympatric genus Polyxena Kunth is discussed, and its inclusion within Lachenalia is supported. The aim of the study was to examine the potential of morphological characters in producing a natural classification of Lachenalia. A morphological cladistic analysis of Lachenalia has not previously been attempted. A wide range of characters was analysed, including macromorphology, micromorphology, anatomy and palynology. Two parsimony analyses were performed using the endemic southern African genus Massonia Thunb. ex Houtt as the ancestral outgroup; an initial analysis in which the characters were unweighted, and a weighted analysis using successive approximations character weighting. The high level of homoplasy evident in both analyses indicates that morphological characters on their own are insufficient to trace the evolutionary history of Lachenalia, and other approaches such as molecular and cytological methods will need to be used in conjunction with morphology in order to generate a robustly supported, phylogeny of the genus. The study was based on species in their natural habitats as well as under cultivation, and from representative herbarium specimens.