Systematic studies in the tribe Amaryllideae (Amaryllidaceae)

Snijman, D A

Systematic studies in the tribe Amaryllideae (Amaryllidaceae)

Thesis / Dissertation

1992

Abstract

Systematic studies in the tribe Amaryllideae (Amaryllidaceae). D.A. Snijman, Compton Herbarium, National Botanical Institute, Private Bag X7, Claremont 7735, South Africa. The phylogeny of the African Amaryllideae is presented as a basis for classification and an enquiry into the tribe's evolution. The focus is on the monotypic Kamiesbergia Snijman and Carpolyza Salisb., Hessea Herbert (nine species), Namaquanula D. & U. Muller-Doblies (three species) and Strumaria Jacq. (23 species), for which a full taxonomic treatment is given. The phylogenetic data are used to assess the biotic history of south western Africa; to analyse the constraints and potentialities available to taxa for reproductive strategies; and to gauge putative modes of lineage diversification. Data from bulb and leaf morphology, floral anatomy, pollen, external seed morphology and chromosome cytology were analysed cladistically. The strict consensus tree for Amarytlideae provided a template to trace character evolution. The strict consensus trees for Namaquanu/a, Hessea and Strumaria provided the basis for the cladistic biogeographic analysis, and identified sister-groups for analysing patterns of lineage diversification. The phylogenetic hypothesis indicates that, as previously circumscribed, subtribe Crininae Traub is paraphyletic. The emended Crininae includes Crinum L., Boophane Herbert pro parte, Ammocharis Herbert and Cybistetes Milne-Redhead & Schweickerdt. Strumariinae Traub ex D. & U. Muller-Doblies is incorporated into Amarytlidinae, which now includes Amaryllis L., Nerine Herbert, Brunsvigia Heist., Boophane pro parte, Kamiesbergia, Namaquanula, Hessea, Carpolyza and Strumaria. Tedingea D. & U. Muller-Doblies, Bokkeveldia D. & U. Muller-Doblies and Gemmaria Salisb. are placed into synonymy under Strumaria. The cladistic biogeographic analyses resulted in conflicting patterns. Although uninformative in themselves they may provide a basis for future comparative studies. Rapid lineage diversification is hypothesised for Strumaria through peripheral isolation. Large scale allopatry and founder events are hypothesised for Hessea. In Amaryllidinae the derived stomatose seed is hypothesised to be a key innovation which promoted the evolution of other xerophilous characters: hysteranthous leaves, autumn-flowering, small plant size and few leaves. This permitted rapid diversification in the Mediterranean-type climate of southern Africa. The more slowly developing seed of Crininae is interpreted as a constraint to the occupancy of the Mediterranean-type climatic region. Crininae evolved rapidly in the summer-rainfall regions of Africa, where the speciose Crinum evolved the contrasting hydrophilic habit as a drought-avoidance strategy.

Keywords

Biological Sciences

Reference:

Collections

PhD / Doctoral

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