Pityrogramma argentea vs fern

Pityrogramma argentea and fern both are nouns.

Word	Noun	Adjective	Verb	Adverb
Pityrogramma argentea	Yes	No	No	No
fern	Yes	No	No	No

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

Pityrogramma argentea: fern of southern tropical Africa having fronds with white undersides
fern: any of numerous flowerless and seedless vascular plants having true roots from a rhizome and fronds that uncurl upward; reproduce by spores

Pityrogramma argentea (noun)	fern (noun)
fern of southern tropical Africa having fronds with white undersides	any of numerous flowerless and seedless vascular plants having true roots from a rhizome and fronds that uncurl upward; reproduce by spores