Barbwire Russian thistle dominated a degraded plant community in the Carson Desert of northwestern Nevada and completely excluded Russian thistle in the course of the study. In seeding trials barbwire Russian thistle became established at low levels under arid conditions of the desert while Russian thistle failed to become established. Under semiarid conditions, seedling establishment of Russian thistle was five time greater than that of barbwire Russian thistle. Adaptations of barbwire Russian thistle that apparently favor seedling establishment under arid desert environments include earlier maturation and seed dispersal, seed dispersal beneath the parent plant, and less specific afterripening requirements than Russian thistle. These adaptations would permit germination and seedling establishment in the relatively wet periods of late winter and early spring in this arid ecosystem.