The Collaborative International Dictionary of English v.0.48:

Cleistogamic \Cleis`to*gam"ic\, Cleistogamous
\Cleis*tog"a*mous\a. [Gr. ? closed (fr. ? to shut) + ga`mos
   marriage.] (Bot.)
   Having, beside the usual flowers, other minute, closed
   flowers, without petals or with minute petals; -- said of
   certain species of plants which possess flowers of two or
   more kinds, the closed ones being so constituted as to insure
   self-fertilization. --Darwin.
   [1913 Webster]

WordNet (r) 3.0 (2006):

cleistogamous
    adj 1: exhibiting or relating to cleistogamy [syn:
           cleistogamous, cleistogamic]