Reproductive Strategies, Seed Production, and Ploidy Levels of Four Notable Invasive Plant Species

Plant invasion occurs when a species disperses to areas outside its native range as an introduced species. These introduced plant species establish self-sustaining populations and become naturalized. Subsequently, these naturalized species expand their populations, dominate ecosystems, and spread across wide areas as invasive species. Successful invasive species must adapt to novel environmental conditions and reproduce abundantly. However, because introduced populations tend to be small and experience a significant reduction in genetic variation due to bottlenecks, those relying on outcrossing may fail to produce fertile seeds owing to a lack of suitable pollinators or insufficient density of conspecifics. This review discusses the genetic makeup, reproductive strategies, and adaptability to different environmental conditions of four notable globally invasive plant species: Pueraria montana var. lobata, Reynoutria japonica, Mimosa pigra, and Robinia pseudoacacia. Although each species possesses a unique genetic makeup and reproductive strategy, they all exhibit high physiological and morphological plasticity within their introduced range. This plasticity may result from multiple introductions from different native sources, polyploidization, and/or cross-pollination mediated by various pollen vectors. Consequently, these traits enable them to adapt to different environmental conditions, facilitating the successful establishment and expansion of their populations in new habitats.