BIOLOGY OF GREWIA-TENAX COMPLEX (TILIACEAE) FROM PAKISTAN

Grewia tenax (Forssk.) Fiori was hitherto considered as a highly polymorphic taxon. A biological study of this complex from Pakistan indicates the existence of two distinct taxa viz., G. tenax(Forssk.) Fiori and G. erythraea Schweinf. G. tenax is characterized by having taller growth habit, ovate-acute leaves and deeply 4-lobed glabrous ovary; while G. erythraea is delimited by smaller individuals with obovate-obtuse leaves and entire densely hairy ovary. Two taxa also differ on the basis of chemical and palynological characters. Both the species are facultative xenogamous, sympatric in distribution and the flowering period is also overlapping in southern Pakistan. An intermediate and fairly heterogeneous population was also found, thus indicating a possibility of a limited hybridization taking place with a limited exchange of genes in southern Pakistan.