XVI International Botanical Congess

Rheophytes are plant species adapting at riverbeds. To know about genetic diversity and population differenti- ation of rheophytes, we examined allozymic variations of two Sumatran endemic species of Araceae. Furtadoa sumatrensis and Schismatoglottis okadae are distributed widely in West Sumatra. They propagate by outcrossed seeds and rhizome branching. Lower gene diversity of populations and higher population differentiation were observed at both species as compared with a land species, F. mixta. Observed heterozygosities of F. sumatrensis populations were various. The phenogram based Nei's genetic distance showed that these two species had quite different aspects on relations among populations. Genetic distances between populations of F. sumatrensis were larger in proportion to geographical distances, while S. okadae had no correlation.