Taxonomic Revision of Heliotropium L. (Boraginaceae s.l.) in South of Yemen
5 December 2014
El Naggar, Salah; El Hadidy, Azza; Olwey, AsmaaThe genus Heliotropium L. (Boraginaceae) in south Yemen has been revised taxonomically, ten species were recognized. The nomenculature, typification, representative specimens and a diagnostic key for the each species and their distribution in south Yemen are provided. The most valuable taxonomic characters were those of the flower (calyx, corolla, androecium and gynoecium) and of the nutlet. Both light and scanning microscopy have been used in the investigation. Deep or shallow ventral circular depressions on the nutlets were found to be useful in distinguishing members of section Orthostachys (viz. H. strigosum, H. rariflorum and H. ovalifolium), while the winged nutlets were found only in H. pterocarpum. Papillate anther apices were recognized in some species.