Source : Webster's Revised Unabridged Dictionary (1913)

Verticil \Ver"ti*cil\, n. [L. verticillus, dim. of vertex a
   whirl: cf. F. verticille. See {Vertex}.] (Bot.)
   A circle either of leaves or flowers about a stem at the same
   node; a whorl. [Written also {verticel}.]

Source : WordNet®

verticil
     n : a whorl of leaves growing around a stem