Spontaneous hybridization of Potamogeton praelongus and Potamogeton lucens confirmed in a germination test (Czech Republic)

A hybrid of P. praelongus and P. lucens (P.×jutlandicus) was found in an outdoor germination test in 2013-2015, which confirmed existence of spontaneous hybridization of the pondweed species present in the ponds below Plešivec in the Kokořínsko Protected Landscape Area in the Czech Republic. Seedlings of P. ×jutlandicus were different from those of P. praelongus and the speed of their growth was higher. P. ×jutlandicus has not been found in natural sites in the Czech Republic yet. The Czech locality is the third one of this rare hybrid worldwide and the first one with a molecular proof.