A Newly Discovered Species of the Family Asteraceae in Nigeria

20 February 2019

Adegbite, Adegoke; Ojo, Funmilola; Abraham, Olubukola; Francis, Joseph; Balogun, Sunday

A plant that showed morphological closeness to Aspilia africana (Pers) C. D. Adams (Asteraceae) was spotted and collected in the year 2015 along Afe Babalola University road, Ado-Ekiti, Ekiti state, Nigeria with coordinates 7º36’59.99N, 5º12’60.00E. A closer observation on the plant revealed some distinct and peculiar characteristics such as sterility of the disc florets and production of achenes by ray florets only that distinguished it clearly from Aspilia africana. Another striking character of the plant is total emptying of the capitulum after achene maturation, leaving empty capitulum cup on the plant. Literature and herbarium searches revealed that the plant has neither been reported in West Tropical Africa nor collected in any herbarium in Nigeria. The plant was eventually identified through literatures and Kew Gardens as Melampodium divaricatum (L.) which is an annual erect herb, distributed in tropical and subtropical regions, mostly restricted to Mexico, North America and Central America. M. divaricatum belongs to the family Asteraceae, tribe Heliantheae and genus Melampodium. The genus contains about 45 species. Preliminary morphological, reproductive biology and cytological studies carried out on the plant revealed it to possess highly branched erect pigmented stem, simple opposite sub sessile leaves with acute apex and distantly serrated margins, capitula with yellow unisexual disc and ray florets, sterile disc florets, fertile ray florets, relatively high pollen fertility (92.85%), somatic chromosome counts of 2n=24 and regular formation of 12 bivalents, indicating the plant to be a diploid species. Further searches and studies are suggested for other species of Melampodium which is being reported in Nigeria for the first time, and indeed, a general review of the Flora of West Tropical Africa.