The Collaborative International Dictionary of English v.0.48:

Peltate \Pel"tate\, Peltated \Pel"ta*ted\, a. [Cf. F. pelt['e].
   See Pelta.]
   Shield-shaped; scutiform; (Bot.) having the stem or support
   attached to the lower surface, instead of at the base or
   margin; -- said of a leaf or other organ. -- Pel"tate*ly,
   adv.
   [1913 Webster]

WordNet (r) 3.0 (2006):

peltate
    adj 1: (of a leaf shape) round, with the stem attached near the
           center of the lower surface rather than the margin (as a
           nasturtium leaf for example) [syn: peltate, shield-
           shaped]