PATTERNS OF DIVERSIFICATION AND EVOLUTION IN PHYLLANTHUS-ODONTADENIUS(EUPHORBIACEAE)

Experimental crossings within Phyllanthus subsect. Odontadenii reveal different levels of reproductive incompatibility between taxa of varyi ng morphological distinction. Some of tbe reproductive barriers may be circumvented using in vitro culture. Cytological and morphological st udies of the progeny of experimental crosses has yielded information a bout the processes of differentiation of taxa within subsection Odonta denii, as well as within the Phyllanthus urinaria complex. The results of this study support the recognition of taxa earlier proposed in the se two complexes, and furthermore document the existence of a tetraplo id taxon (Phyllanthus magnificens) with a base chromosome number of x = 10.