Taxonomic circumscription of the Nigerian material of Ipomoea pileata is suggested owing to its uniqueness from the Asian and other African specimens. Cotyledon size, presence or absence of inner, sepal?like bracts, sepal's shape, colour and size of corolla, stigma colour and number of flower per involucre?bract among others are diagnosticable. Evolutionary mechanisms leading to speciation in Ipomoea sect. Involucrutae include shortening of life cycle with development of long seed dormancy period, variation of flower opening and closing periods, reduction in size and number or loss of floral part(s), inbreeding and geographical isolation. Chromosome counts revealed 2n= 30 with different lengths (P < 0>Ipomoea involucrata P. BEAUV.var. involucrata f. bicolor OGUNWENMO f. nova is described.