Investigation of morphology, karyotype, isozymes, cultivation, geography and habitat confirmed differences between Limbella tricostata (Sull.) CM. and Sciaromium fryei Williams. Significant differences were observed experimentally in branch bud frequency, leaf insertion angle, leaf areolation, chromosome length, mobility of superoxide dismutase and shoot orientation. Sciaromium fryei is considered a subspecies of Limbella tricostata. Chromosome numbers of both subspecies is n=11. L. tricostata ssp. tricostata has a Bryum type sporeling and a hypnaceous peristome, and is thought to have derived from L. pachyloma (Mont.) C.M. or its antecedent after long-distance dispersal from South America to Hawaii no later than the mid-Tertiary. L. tricostata ssp. fryei is thought to have derived from L. tricostata ssp. tricostata after long-distance dispersal from Hawaii to North America in the mid- to late Tertiary. / Science, Faculty of / Botany, Department of / Graduate