strap fern vs fern

strap fern and fern both are nouns.

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

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

strap fern: fern with long narrow strap-shaped leaves
fern: any of numerous flowerless and seedless vascular plants having true roots from a rhizome and fronds that uncurl upward; reproduce by spores

strap fern (noun)	fern (noun)
fern with long narrow strap-shaped leaves	any of numerous flowerless and seedless vascular plants having true roots from a rhizome and fronds that uncurl upward; reproduce by spores