Rarity and vulnerability are assumed to be linked but persisting rare flora may possess mechanisms for coexistence. The nationally endangered Viola praemorsa disappears with too much forest cover (tree invasion by fire suppression) or not enough (prairie expansion by climate change), suggesting it is perched on the edge of extirpation. Yet its mixed-breeding system and dispersal characteristics may give it flexibility to adapt and persist depending on conditions (e.g., competition, climate change, herbivory). Long-term demographic and experimental work is determining whether this species is stable, or doomed to disappear. Project emphases include the importance of ant dispersal on spatial patterning in habitat remnants, how its mixed-breeding system responds to manipulations of interannual and seasonal climatic variability, the interaction between stochastic and deterministic regulatory mechanisms on population dynamics, and how pollinator dynamics are influenced by native diversity vs. grass invasion.