Allozyme variation in the endangered plant Clematis socialis and a closely related species (C. crispa) was examined by horizontal starch gel electrophoresis. Two populations of each species were sampled for allelic variation at seven loci to estimate genetic diversity. The relative contribution of clonal growth and seedling recruitment to maintenance of C. socialis populations also was estimated from the electrophoretic results by calculating genotypic diversity. Both species possessed moderate levels of genetic diversity: mean expected heterozygosity (H_e) was 0.302 for C. socialis and 0.246 for C. crispa. Analysis of multilocus genotypic diversity revealed 26 distinct genotypes among 55 individuals of Clematis socialis, and 22 different genotypes for 37 individuals of C. crispa. The genetic diversity of C. socialis is more consistent with values reported for nonclonal plants, and levels of multilocus genotypic diversity suggest that considerable sexual reproduction has occurred in these populations despite low levels of observed seedling recruitment.