[f. SPIKE sb.2] A small spike or spike-shaped object; a prickle or thorn.

1

1851.  Mayne Reid, Scalp Hunt., xxvii. 203. We carefully pare off the volutes and spikelets [of the cacti].

2

1876.  trans. Wagner’s Gen. Pathol., 121. The surface of the body is covered with little spikelets.

3