The Collaborative International Dictionary of English v.0.48:

Uniovulate \U`ni*o"vu*late\, a. [Uni- + ovulate.] (Bot.)
   Containing but one ovule.
   [1913 Webster]

WordNet (r) 3.0 (2006):

uniovulate
    adj 1: having a single ovule [syn: uniovular, uniovulate]