Osmunda regalis

Royal fern (Osmunda regalis) is a species of Osmunda, native to Europe, Africa and Asia and the Americas, growing in woodland bogs. The species is sometimes known as flowering fern due to the appearance of its fertile fronds.

It is a deciduous herbaceous plant which produces separate fertile and sterile fronds. The sterile fronds are spreading, 60-160 cm tall and 30-40 cm broad, bipinnate, with 7-9 pairs of pinnae up to 30 cm long, each pinna with 7-13 pairs of pinnules 2.5-6.5 cm long and 1-2 cm broad. The fertile fronds are erect and shorter, 20-50 cm tall, usually with 2-3 pairs of sterile pinnae at the base, and 7-14 pairs of fertile pinnae above bearing the densely-clustered sporangia.

The name derives from its being one of the largest and most imposing European ferns. In many areas, it has become rare as a result of wetland drainage for agriculture. (from Wikiipedia)