The Collaborative International Dictionary of English v.0.48:

Spikelet \Spike"let\, n. (Bot.)
   A small or secondary spike; especially, one of the ultimate
   parts of the in florescence of grasses. See Illust. of
   Quaking grass.
   [1913 Webster]

WordNet (r) 3.0 (2006):

spikelet
    n 1: a small sharp-pointed tip resembling a spike on a stem or
         leaf [syn: spine, thorn, prickle, pricker,
         sticker, spikelet]