flowers-of-an-hour vs flower-of-an-hour

flowers-of-an-hour and flower-of-an-hour both are nouns.

Word	Noun	Adjective	Verb	Adverb
flowers-of-an-hour	Yes	No	No	No
flower-of-an-hour	Yes	No	No	No

As nouns, flowers-of-an-hour and flower-of-an-hour are synonyms defined as:

flowers-of-an-hour and flower-of-an-hour: annual weedy herb with ephemeral yellow purple-eyed flowers; Old World tropics; naturalized as a weed in North America

Other synonyms of flowers-of-an-hour include black-eyed Susan, bladder ketmia, Hibiscus trionum.

flowers-of-an-hour (noun)	flower-of-an-hour (noun)
annual weedy herb with ephemeral yellow purple-eyed flowers; Old World tropics; naturalized as a weed in North America	annual weedy herb with ephemeral yellow purple-eyed flowers; Old World tropics; naturalized as a weed in North America