Abstract: Improving reproductive ability of invasive plants might be an important mechanism for successful invasion,but there might be different in variation of reproductive organ traits among the different habitats,especially in the trade-off relationship.The plant Plantago virginica was taken as material,the inflorescences in three habitats including lawn,wasteland and understory,were collected to investigate the differences of morphology,biomass,and the allometric relationship of spikelet and peduncle among different habitats.The results showed that,there were significant differences in most inflorescence morphological and biomass indexes of P.virginica in different habitats.The inflorescences of P.virginica in lawn and wasteland habitats were slender,while that in understory habitat was short and strong.The allometric relationships among different traits of reproductive organs of P.virginica were both conservative and variable,showing different environmental sensitivities.The size dependence of reproductive resource allocation of P.virginica in different habitats was also inconsistent.Therefore,the inflorescence traits and resource allocation of P.virginica in different habitats are both plastic and relatively conservative,which might be an important manifestation of its high invasive ability.