flora (n.)

c. 1500, "Roman goddess of flowers;" 1777, "the plant life of a region or epoch," from Latin Flora, "goddess of flowers," from flos (accusative florem, genitive floris) "flower," from *flo-s-, Italic suffixed form of PIE *bhle- "to blossom, flourish" (source also of Middle Irish blath, Welsh blawd "blossom, flower," Old English blowan "to flower, bloom"), extended form of root *bhel- (3) "to thrive, bloom."

Her festival, the Floralia, was April 28 to May 2 and featured "comic theatrical representations" and "excessive drinking" [Century Dictionary]. The French Revolutionary calendar had a month Floréal (April 20-May 20). Used as the title of systematically descriptive plant catalogues since 1640s, but popularized by Linnaeus in his landmark 1745 study of Swedish plants, "Flora Suecica."