Variation of acacia senegal and its relationship with acacia circummaginata and acacia thomasii in Kenya

Abstract

Four growth forms previously recognized as constituting three of the four varieties within Acacia senegal (L.) Willd. were carefully observed in their natural environment in Kenya and their habits and habitats recorded and presented in form of photographs. Herbarium specimens from the species range in South and North-East Tropical Africa were critically examined and all measurable morphological parameters compared for similarities, differences and variations. The previous relationship of A. senegal to A. circummaginata was discussed and reassessed as were the apparent similarities between one of the previously recognized growth form of A. senegal and A. thomasii. From the field observations of living trees and the herbarium examination of dry specimens, variation within A. senegal was found not as much as previously perceived. The two growth forms, previously considered as constituting A. senegal var. leiorhachis were found to be identifiable as distinct and different taxa from A. senegal. It was recommended that the growth form with rounded spreading crown retain its original name A. circummaginata while a new name A. flagellum nom. novo for the whippy growth form was suggested. The large flowers and lack of rachis glands were found to be the most reliable characters for distinguishing A. thomasii from this latter taxa.