The Collaborative International Dictionary of English v.0.48:

Verticillate \Ver*tic"il*late\ (?; 277), Verticillated
\Ver*tic"il*la`ted\, a. [See Verticil.] (Bot. & Zool.)
   Arranged in a transverse whorl or whorls like the rays of a
   wheel; as, verticillate leaves of a plant; a verticillate
   shell.
   [1913 Webster]

WordNet (r) 3.0 (2006):

verticillate
    adj 1: forming one or more whorls (especially a whorl of leaves
           around a stem) [syn: verticillate, verticillated,
           whorled]