Source : Webster's Revised Unabridged Dictionary (1913)

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}.

Source : WordNet®

spikelet
     n : a small spike (as the inflorescence on grasses and sedges)