common polypody

Polypodium vulgare, the common polypody, is a fern of the Polypodiaceae family. Polypodium vulgare is an allotetraploid species, believed to have arisen by chromosome doubling of a sterile diploid hybrid between two ferns which are not known in Europe. The fern's proposed parents are the northern Asian and northern North American Polypodium sibiricum and western North American Polypodium glycyrrhiza. Biochemical data point to a species from eastern Asia as the second possible parent. The name is...