Interference between two floating-leaved aquatic plants: Nymphoides peltata and Trapa bispinosa

A 12-week microcosm experiment was conducted to identify the intraspecific and interspecific interference abilities of two floating-leaved aquatic plants Nymphoides peltata (Gmel.) O. Kuntze and Trapa bispinosa Roxburgh. N. peltata exerted a strong interspecific interferential effect on T. bispinosa, but the opposite was not apparent. There existed an intraspecific interferential effect of T. bispinosa on itself, although the interspecific interference of N. peltata was stronger. No apparent intraspecific interference was found among the individual plants of N. peltata. The removal of N. peltata had a positive impact on growth and performance of T. bispinosa, whereas no apparent impacts were found in the removal of T. bispinosa on growth and performance of N. peltata. Moreover, both the removal of N. peltata and T. bispinosa did not show apparent effects on growth of the remaining individuals of the species themselves. These results suggest that N. peltata has distinct interferential advantages over T. bispinosa and that this depends mainly upon the differences between the two species in morphology and life history.