Source : Webster's Revised Unabridged Dictionary (1913)

Apocynaceous \A*poc`y*na"ceous\, Apocyneous \Ap`o*cyn"e*ous\, a.
   [Gr. ? dogbane; ? from + ? dog.] (Bot.)
   Belonging to, or resembling, a family of plants, of which the
   dogbane ({Apocynum}) is the type.

Source : WordNet®

apocynaceous
     adj : of or relating to tropical plants of the family Apocynaceae