[Wikipedia] Taxonomy: The species name of this fern, expansa, is from the Latin expando, meaning "to spread out, spread apart, to expand". Other common names include northern wood fern, arching wood fern, spiny wood fern and crested wood fern. The Finnish name is isoalvejuuri which directly translates to "large cestoda root" likely referring to its relations to use of other buckler ferns as worm expellent in traditional Finnish medicine especially Dryopteris filix-mas. (link added by Mary Ann Machi)