Source : Webster's Revised Unabridged Dictionary (1913)

Senecio \Se*ne"ci*o\, n. [L., groundsel, lit., an old man. So
   called in allusion to the hoary appearance of the pappus.]
   (Bot.)
   A very large genus of composite plants including the
   groundsel and the golden ragwort.

Source : WordNet®

Senecio
     n : enormous and diverse cosmopolitan genus of trees and shrubs
         and vines and herbs including many weeds [syn: {genus
         Senecio}]