ABSTRACT This study investigated several ecological parameters for populations of Obolaria virginica in southeast Missouri where it is listed as endangered. Investigations during the 2006 and 2007 growing seasons included population size estimates and dispersal patterns. A secondary investigation during the 2007 season quantitatively assessed the impact of leaf litter on O. virginica flower production. Obolaria virginica reflected the pattern of a spring ephemeral with emergence as early as mid-February and senescence by early June. Plants grew to an average of 9.2 cm in height and had 14 flowers per individual in each season. Population size estimates ranged from 833–7,820 individuals, with a distinctly clumped distribution pattern. Leaf litter depth appears to negatively affect emergence and flower production in this perennial forest herb.