annulus vs plant structure

annulus and plant structure both are nouns.

Word	Noun	Adjective	Verb	Adverb
annulus	Yes	No	No	No
plant structure	Yes	No	No	No

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

annulus: (Fungi) a remnant of the partial veil that in mature mushrooms surrounds the stem like a collar
plant structure: any part of a plant or fungus

Other hypernyms of annulus include plant part.

annulus (noun)	plant structure (noun)
(Fungi) a remnant of the partial veil that in mature mushrooms surrounds the stem like a collar	any part of a plant or fungus
a toroidal shape