A taxonomic investigation of variation within Cissus quadrangularis L. (Vitaceae) in Kenya.
Using information from literature as well as records of localities on herbarium specimen labels at the East African Herbarium Nairobi, materials of C. quadrangularis, C. cactiformis and C. quinquangularis were collected and new localities were sought. On the basis of the nature of their stem angles, the specimens of C. quadrangularis were sorted into two variants, A and B. Variant A has smooth stem angles while variant B has rough stem angles. The authors have proposed that variant B should be recognized as a new variety within C. quadrangularis. Variant A is the type variety of C. quadrangularis. A map showing the distribution of the two variants in Kenya has been prepared. The rough-edged variant was found to be absent from the low-lying semiarid regions of northern Kenya. The variants were found occurring in distinct, separate populations but without separate geographical patterns. The results of t-test show no significant difference (P=0.05) between the means of measurements of dimensions of various organs in the two variants. The stem angles of specimens of the two variants were studied under scanning electron microscope. This showed a clear morphological difference between the two variants. The results of the investigation support the hypothesis that the variation within C. quadrangularis represents distinct kinds that can be recognized as taxa at infraspecific level.