The Commelinaceae of West Africa: A biosystematic survey

All the known West African taxa are surveyed and their variation and distribution is discussed. Chromosome numbers for most of the taxa are given, in many cases for the first time, and published cytological data for those genera occurring in West Africa is reviewed. Many of the taxa have been studied under cultivation and most under living conditions in the field. The results of these observations are considered in relation to the evolution of new variations and to the taxonomy of the groups concerned. The following new taxa are described: Aneilema beniniense subsp. leonense, C'ommelina diffusa subsp. montana, Floscopa africana subsp. petrophila and Slanfieldiella axillaris. Several nomenclatural changes have been made, the most important being the recognition that the African species Commelina gerrardi C. B. Clarke and C. vogelii C. B. Clarke are conspecific with the American C. erecta Linn, which thus becomes a pantropie species complex. Several species are recorded from West Africa for the first time including: Coleolrype kiurentii K. Schum. Commelina carsonii C. B. Clarke, C. zambesiaca C. B. Clarke, Cyanotis arachnoidea C. B. Clarke, and Palisota lagopus Mildbr. The pattern of variation in the larger species complexes in the genera Aneilema, Commelina, Cyanotis and Floscopa is considered in detail. These and other groups in the family are considered to be in an active state of evolutionary change. The factors which have stimulated these changes and the biological processes by means of which they are brought about are discussed. Attention is drawn to the suitability of this family for evolutionary studies and its value in the teaching of experimental taxonomy in the tropics.