flower (n.)
c.1200, from Old French flor "flower, blossom; heyday, prime; fine flour; elite; innocence, virginity" (Modern French fleur), from Latin florem (nominative flos) "flower" (source of Italian fiore, Spanish flor; see flora).

Modern spelling is 14c. Ousted Old English cognate blostm (see blossom (n.)). Also used from 13c. in sense of "finest part or product of anything" and from c.1300 in the sense of "virginity." Flower children "gentle hippies" is from 1967.
flower (v.)
c.1200, "be vigorous, prosper, thrive," from flower (n.). Of a plant or bud, "to blossom," c.1300. Related: Flowered; flowering.