Rare events in some species of Aspilia (Thouars) (Heliantheae asteraceae)
ASSET Series A Agriculture and Environment 3(2): 47-55
Species in the genus Aspilia are known to have opposite-decussate leaves, chromosome number of n=14 (2n=28) and sterile ray achenes. Rare expressions of these characters were observed in the course of a biosystematic study on the Nigerian species of Aspilia. The rare events are whorled leaf arrangement in A. helianthoides, viable ray achenes in A. kotschyi and polytene chromosomes in A. africana. The phenotypic, genetic and taxonomic implications of the rare events are discussed. These rare events are probably mutations that represent potentials for evolution of new species (or genotypes) and adoption of apomixis in the genus Aspilia.