AN ALLOZYME STUDY OF 2 SIBLING SPECIES OF LEMNA (LEMNACEAE) WITH COMMENTS ON THEIR MORPHOLOGY, ECOLOGY AND DISTRIBUTION

Enzyme electrophoresis was employed to examine divergence between Lemn a minuta H.B.&K. and valdiviana Phil., two nearly indistinguishable sp ecies comprising sect. Uninerves of Lemna. Fifteen presumptive loci we re resolved for 25 clones of Lemna minuta and 26 of L. valdiviana. Gen etic identity between the two species is 0.70, which is near the mean value for congeneric species of flowering plants, but is much higher t han values reported for other species of Lemnaceae. With the exception of two clones, the taxonomic designations of the strains correlated w ith monomorphism for alternative alleles at two MDH loci. The two spec ies are highly differentiated at two other loci as well. Although the tars are morphologically similar, they differ in geographic distributi on, flavonoid chemistry, and certain physiological and ecological attr ibutes. The relatively high identity at allozyme loci compared to othe r Lemnaceae suggests that L. minuta and L. valdivina are closely relat ed and recently diverged sister species.