2002). Although the biological features of aquatic plants are similar to their terrestrial relatives, the adaptive significance maybe dif ferent. One example relates to photosynthesis characteristics: l is generally accepted that C4 and plants evolved in warm and high light areas (Hatch and Slack, 1966: Raghavendra and Sage. 2011 while CAM plants evolved in arid areas (Cushman and Bohnert, 1999; Silvera et al. 2010). But some aquatic plants similar biochemical feature (Maberly and Madsen, 2002; Zhang et al.. 2014 Keeley this issue; Raven and Bearda this issue light-limiting (especially for sub- even if they live in a water-rich, mersed plants) environment in order to minimize mitation of photosynthesis by inorganic carbon. We need to consider the dif ferent adaptive meaning of such characteristics of aquatic plants in general and also when considering aquatic plant reproduction and dispersal