Effects of origin and water depth on morphology and reproductive modes of the submerged plant Vallisneria natans

• The decline of submerged macrophytes in shallow lakes and wetlands has cascade effects on regional and global biodiversity. In the last two decades, the rapid disappear of macrophyte beds in the floodplain lakes of the middle lower Yangtze River has become a great concern for the ecological security of the region. • This study aims to quantify the effects of water depth on biomass production and clonal (i.e. stolons and winter buds) and sexual reproduction (i.e. fruits) of Vallisneria natans, a cosmopolitan, perennial submergent species. • Results of the research clearly demonstrated the unimodal relationship between biomass production and water depth, and there was an optimal range of 35–50 cm, beyond which total biomass decreased. Also, both clonal and sexual reproductive outputs decreased with water depth. Furthermore, for the first time, the study revealed the distinct reproduction patterns of the individuals originated from seeds and clonal propagules. While seed-generated plants produced significantly more fruits (and no winter buds), plants developed from clonal propagules produced more stolons and winter buds. • There findings plead further researches on V. natans seedling establishment and reproductive ecology because of the importance of winter buds as food for wintering waterbirds in the middle Yangtze floodplains.