Surely this is not a fern?? Yes it is!! It's an unusual hardy fern that can be used as an aquatic plant or planted as a bog garden plant in full sun or light shade. Maximum depth of water is 25cm. If planted at the surface the four leaf clover-like fronds stand upright, up to 15cm high, if planted underwater most will float on the surface with a few standing upright.
It creeps along with its rhizomes to make an unusual ground cover, an ideal bog plant. Noone will believe you when you tell then they are ferns.