blue-eyed Mary vs wild flower

blue-eyed Mary and wild flower both are nouns.

Word	Noun	Adjective	Verb	Adverb
blue-eyed Mary	Yes	No	No	No
wild flower	Yes	No	No	No

As nouns, wild flower is a hypernym of blue-eyed Mary; that is, wild flower is a word with a broader meaning than blue-eyed Mary:

blue-eyed Mary: eastern United States plant with whorls of blue-and-white flowers
wild flower: wild or uncultivated flowering plant

Other hypernyms of blue-eyed Mary include wildflower.

blue-eyed Mary (noun)	wild flower (noun)
eastern United States plant with whorls of blue-and-white flowers	wild or uncultivated flowering plant