gay-feather vs wild flower

gay-feather and wild flower both are nouns.

Word	Noun	Adjective	Verb	Adverb
gay-feather	Yes	No	No	No
wild flower	Yes	No	No	No

As nouns, wild flower is a hypernym of gay-feather; that is, wild flower is a word with a broader meaning than gay-feather:

gay-feather: any of various North American plants of the genus Liatris having racemes or panicles of small discoid flower heads
wild flower: wild or uncultivated flowering plant

Other hypernyms of gay-feather include wildflower.

gay-feather (noun)	wild flower (noun)
any of various North American plants of the genus Liatris having racemes or panicles of small discoid flower heads	wild or uncultivated flowering plant