chain fern vs fern

chain fern and fern both are nouns.

Word	Noun	Adjective	Verb	Adverb
chain fern	Yes	No	No	No
fern	Yes	No	No	No

As nouns, fern is a hypernym of chain fern; that is, fern is a word with a broader meaning than chain fern:

chain fern: a fern of the genus Woodwardia having the sori in chainlike rows
fern: any of numerous flowerless and seedless vascular plants having true roots from a rhizome and fronds that uncurl upward; reproduce by spores

chain fern (noun)	fern (noun)
a fern of the genus Woodwardia having the sori in chainlike rows	any of numerous flowerless and seedless vascular plants having true roots from a rhizome and fronds that uncurl upward; reproduce by spores