common maidenhair vs maidenhair

common maidenhair and maidenhair both are nouns.

Word	Noun	Adjective	Verb	Adverb
common maidenhair	Yes	No	No	No
maidenhair	Yes	No	No	No

As nouns, maidenhair is a hypernym of common maidenhair; that is, maidenhair is a word with a broader meaning than common maidenhair:

common maidenhair: delicate maidenhair fern with slender shining black leaf stalks; cosmopolitan
maidenhair: any of various small to large terrestrial ferns of the genus Adiantum having delicate palmately branched fronds

Other hypernyms of common maidenhair include maidenhair fern.

common maidenhair (noun)	maidenhair (noun)
delicate maidenhair fern with slender shining black leaf stalks; cosmopolitan	any of various small to large terrestrial ferns of the genus Adiantum having delicate palmately branched fronds