Plant and fish species
The seeds or fruits (the term ‘seed’ will be further used to referto seeds plus fruits) of 19 plant species (Fig. 1) were collected fromnatural populations in late summer 2012. From October 2012 untilMarch 2013, seeds of riparian species were stored dry in vials, andseeds of aquatic species were stored in vials with tap water, both indarkness at a temperature of 5◦C. When the experiments started,all seeds had experienced a cold period of at least 108 days, which isconsidered sufficient to ensure germination in most of the speciestested (Baskin and Baskin, 2014).