Dioicous bryophytes often exist in isolated populations with low rates of sexual reproduction. While most populations contain individuals of both sexes, some species have single-sex populations that depend solely on asexual reproduction for population expansion and persistence. Life history trade-offs can constrain population divergence and the relative investment in growth, asexual and sexual reproduction may differ in single-sex and both-sex populations. A common garden experiment and field observations were used to assess trait variation and determine genetic differences among single-sex and both-sex populations of Marchantia inflexa, a dioicous liverwort. Populations were significantly genetically differentiated, and plants from single-sex and both-sex populations differed in their life history strategies. Plants from single-sex populations invested more in growth than asexual production, and although they produced as many sexual structures, they produced fewer gametangia per gametophore than plants from both-sex populations. Characteristics of female plants were positively correlated with geographic, nearest-neighbor distance, whereas characteristics exhibited by male plants showed no relation to geographic distance. Single-sex populations of M. inflexa in Oklahoma and populations from Florida form a distinct phenotypic group within the species that deserves further study.