Bloom “flower” comes from the Proto-Indo-European root bhel-, bhol-, bhlē-, bhlō- (with still other variants) “to bloom, thrive.” Initial Proto-Indo-European bh- usually becomes b- in the Germanic languages, f- in the ancient Italic languages (Latin, Oscan, Umbrian), and ph- in Greek. Therefore the root variant bhlō- yields Latin flōs (inflectional stem flōr- ) “flower” and its derivatives flōrēre “to blossom, bloom” and flōrescere “to come into bloom,” from which English derives florescence and florescent. Flower and flour, which English borrowed from Old French, were originally only spelling variants. The root variant bhol- yields folium in Latin and phúllon in Greek, both meaning “leaf.”

Did you mean bloodless?