Source : Webster's Revised Unabridged Dictionary (1913)

Runcinate \Run"ci*nate\, a. [L. runcinatus, p. p. of runcinare
   to plane off, fr. runcina a plane.] (Bot.)
   Pinnately cut with the lobes pointing downwards, as the leaf
   of the dandelion.

Source : WordNet®

runcinate
     adj : having incised margins with the lobes or teeth pointing
           toward the base; as dandelion leaves