Systematic studies in the Gloriosa superba complex (Colchicaceae): a re-assessment of species boundaries

Abstract

Background and aims – Gloriosa superba L. is a highly variable species occurring in a wide range of ecological habitats in South Africa, tropical Africa and Asia. The morphological variation in G. superba was found to be complicated and therefore numerical methods were used to re-evaluate morphological variation and species delimitation in the G. superba complex. Methods – This study was based on 79 herbarium specimens from B, BM, BR, C, COI, F, K, L, SRGH, U, UPS and WAG (abbreviations follow Holmgren et al. 1990). Cluster and ordination analyses were used to explore morphological variation within the study group. The morphometric data set based on both qualitative and quantitative characters was entered directly into a computerized matrix and a cluster analysis was computed using NTSYS package. The variability of individual characters was evaluated by box-plots using SPSS. Key results & conclusions – The morphological study has revealed the existence of four phenetic species in the G. superba complex. Recognition of these species is based on habit, inflorescence characters and distribution patterns. It is here proposed that four species should be recognized in the G. superba complex: G. baudii (Terracc.) Chiov., G. carsonii Baker, G. superba L. and G. simplex L. Gloriosa superba is the most widespread taxon, occurring in South Africa, tropical Africa and Asia. Gloriosa simplex, G. carsonii and G. baudii are confined to the African continent, with G. simplex widespread in tropical Africa, G. carsonii common in south, central to east tropical Africa, and G. baudii having the most restricted range, confined to the arid regions of northern Kenya, Ethiopia and Somalia.