Oleandra mollis vs fern

Oleandra mollis and fern both are nouns.

Word	Noun	Adjective	Verb	Adverb
Oleandra mollis	Yes	No	No	No
fern	Yes	No	No	No

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

Oleandra mollis: tropical fern having leathery fronds resembling oleander; found from Asia to Polynesia
fern: any of numerous flowerless and seedless vascular plants having true roots from a rhizome and fronds that uncurl upward; reproduce by spores

Oleandra mollis (noun)	fern (noun)
tropical fern having leathery fronds resembling oleander; found from Asia to Polynesia	any of numerous flowerless and seedless vascular plants having true roots from a rhizome and fronds that uncurl upward; reproduce by spores