SOME PIECES OF THE AFRICAN GENOME PUZZLE IN HIBISCUS SECT. FURCARIA (MALVACEAE)

New chromosome counts are reported for four African diploid species of Hibiscus L. sect. Furcaria DC: H. greenwayi Bak. f., H. hiernianus Exell et Mendonça, and H. mechowii Garcke, n = 18; and H. berberidifolius A. Rich., 2n = 36. Chromosome behavior is described in seven new hybrid combinations. Hibiscus greenwayi is shown to carry an A genome. Hibiscus hiernianus and H. mastersianus have similar genomes which are not homologous with that of H. mechowii. New and earlier data are integrated to elucidate genome relationships among 13 taxa–each of the four tetraploid species has a different formula encompassing 2 of 6 mutually nonhomologous genomes, A, B, G, H, X and Y (H. acetosella Welw. ex Hiern = AABB; H. meeusei Exell = AAXX; H. sabdariffa L. = AAYY; H. rostellatus Guill. et Perr. = GGHH). Diploid donors of A, B, G, X and Y are proposed on the basis of plant, flower and pollen morphology. Diploid carriers of A (H. asper Hook. f., H. cannabinus L., H. greenwayi), B (H. surattensis L.) and G (H. sudanensis Hochr.) have been verified cytologically. Cytological confirmation of X (H. hiernianus, H. mastersianus Hiern) and Y (H. mechowii) carriers is incomplete. No putative diploid carrier of H is at hand. Genome affinities of H. berberidifolius are unknown.