Seed Productivity and Peculiarities of Floating of Generative Diaspores of Some European Species of the Genus Sparganium L.

Resumo

This study presents data on actual seed productivity and the ability to spread generative diaporas of various Sparganium species. It is established that, by decreasing the actual seed-productivity index, Sparganium species are arranged in the following order: S. microcarpum (Neum.) Domin. > S. emersum Rehm. > S. glomeratum (Laest.) Neum. > S. gramineum Georgi. > S. erectum L. > S. hyperboreum Laest. ex Beurl. > S. natans L. The lowest actual seed-productivity indices are recorded in representatives of the Minima section—S. hyperboreum and S. natans, which is caused by the miniaturization of the sizes of these species. Investigations into the floating ability of the fruitlet show that the representatives of the subgenus Sparganium (compared to the representatives of the subgenus Xanthosparganium) have higher buoyancy, which is associated with the higher wall thickness of the stone fruit and the number of air cavities in the pericarp. Unlike other species, the fruitlet of S. gramineum sinks to the bottom of the reservoir after separation from the plant.