perianth vs plant organ

perianth and plant organ both are nouns.

Word	Noun	Adjective	Verb	Adverb
perianth	Yes	No	No	No
plant organ	Yes	No	No	No

As nouns, plant organ is a hypernym of perianth; that is, plant organ is a word with a broader meaning than perianth:

perianth: collective term for the outer parts of a flower consisting of the calyx and corolla and enclosing the stamens and pistils
plant organ: a functional and structural unit of a plant or fungus

Other hypernyms of perianth include cover, covering, natural covering.

perianth (noun)	plant organ (noun)
collective term for the outer parts of a flower consisting of the calyx and corolla and enclosing the stamens and pistils	a functional and structural unit of a plant or fungus