Divergences in reproductive strategy explain the distribution ranges of Vallisneria species in China

• Three Vallisneria species with different ranges co-occur in China.
• We compare reproductive strategies under both natural and experimental conditions.
• These Vallisneria species have divergent reproductive strategies.
• The distribution ranges of Vallisneria species depends on reproductive strategies.
• V. natans is an annual or semelparous plant in China.

Closely related plant species usually have similar characteristics in life history, morphology and reproduction and thus similar requirements for their environment, resulting in intense interspecific competition that may constrain the co-occurrence of congeneric plants. In this study, the reproductive strategies of Vallisneria natans, Vallisneria spinulosa and Vallisneria denseserrulata in China were compared based on studies on natural populations and common garden experiments. Variability in reproductive density (including flowering ramets, spathes, flowers, fruits and seeds) and phenotypic characteristics were significantly higher for V. natans than the other two species. V. spinulosa allocated a considerable proportion of biomass (∼27%) to vegetative reproduction through the formation of turions. V. denseserrulata invested less in both sexual and vegetative reproduction than V. natans or V. spinulosa. The differences in reproductive strategy and phenotypic variation may explain the distribution patterns of the three Vallisneria species in eastern China.