O.E.
blæd "a leaf," but also "a leaf-like part" (of spade, oar, etc.), P.Gmc.
*bladaz (cf. O.Fris.
bled "leaf," Ger.
blatt, O.N.
blað), from PIE
*bhle-to-, suffixed form of
*bhel- "to thrive, bloom" (see
bole). Extended in M.E. to shoulders (c.1300) and swords (1330). The modern use in reference to grass may be a M.E. revival, by infl. of L.
bladum, O.Fr.
bled "corn, wheat." The cognate in Ger.,
blatt, is the general word for "leaf;"
laub is used collectively as "foliage." O.N.
blað was used in ref. to herbs and plants,
lauf in ref. to trees. This may have been the original distinction in O.E., too.