bʰleh₃-
“to bloom, flourish, flower”Source of Latin flōs, English bloom, flower, flourish, flora
Root for blooming, yielding Latin flōs (flower) and English bloom, flower, flourish, flora, blood.
Discussion
*bʰleh₃- is the Proto-Indo-European root meaning "to bloom, to flourish, to flower." The laryngeal *h₃ colours the preceding vowel to *o in some environments, though the root is most often cited in its zero-grade or lengthened forms.
In Latin, the root gave flōs (stem flōr-) "flower," from which English inherits a rich vocabulary: "flower," "flour" (originally the same word — the finest part of ground grain), "flora," "floral," "flourish," and "Florence." The Latin verb flōrēre "to bloom" further extended the family.
In Germanic, the root took a different phonological path. Proto-Germanic *blōaną "to bloom" (with the expected *bʰ > b shift under Grimm's Law) yielded Old English blōwan "to bloom" and blōd "blood" — the connection being that blood is the life-fluid that "blooms" or flows. English "bloom," "blossom," and "blow" (in the archaic sense of flowering) all descend from this root.
Greek φύλλον (phúllon) "leaf" is sometimes compared, though this connection is debated. The semantic range from "flowering" to "blood" is a striking example of how metaphorical extension operates across millennia.
Related Roots
English Words from *bʰleh₃-
These modern English words descend from this root. Each page traces the full journey from PIE to present-day English.