The genus Rubus (Rosaceae) in South Africa. IV. Natural hybridiza­ tion

Abstract

The genus Rubus L. is represented in southern Africa by the subgenera Eubatus Focke and Idaeobatus Focke. A combination o f morphological data, data on the reproductive systems of some collections and meiotic chromosome behaviour indicates that a hybrid swarm in the eastern Transvaal was formed subsequent to the hybridization between R. cuneifolius Pursh. taxon B (subgenus Eubatus) and R. longepedicellatus (C. E. Gust.) C. H. Stirton (subgenus Idaeobatus). Other examples of intra- and intersubgeneric hybridization were found during this study of the South African material. These instances, with examples found in the literature, indicate that the subgeneric subdivisions of Rubus are artificial. Three different methods were used to analyse the meiotic chromosome configurations. The genome relationship system of Alonso & Kimber (1981) and Kimber & Alonso (1981) and the modification of the binomial system of Jackson & Casey (1980) by Spies (1984) proved to be the most sensitive for distinguishing between alio-, segmental alio- and autoploids.

Keywords

• chromosomes
• hybridization
• polyploidy
• reproduction. Rosaceae
• <i>Rubus</i>
• South Africa
• speciation