shepherd's clock vs wild flower

shepherd's clock and wild flower both are nouns.

Word	Noun	Adjective	Verb	Adverb
shepherd's clock	Yes	No	No	No
wild flower	Yes	No	No	No

As nouns, wild flower is a hypernym of shepherd's clock; that is, wild flower is a word with a broader meaning than shepherd's clock:

shepherd's clock: weedy European annual with yellow flowers; naturalized in United States
wild flower: wild or uncultivated flowering plant

Other hypernyms of shepherd's clock include wildflower.

shepherd's clock (noun)	wild flower (noun)
weedy European annual with yellow flowers; naturalized in United States	wild or uncultivated flowering plant