Source : Webster's Revised Unabridged Dictionary (1913)

Bullate \Bul"late\ (b[u^]l"l[asl]t/), a. [L. bullatus, fr. bulla
   bubble.] (Biol.)
   Appearing as if blistered; inflated; puckered.

   {Bullate leaf} (Bot.), a leaf, the membranous part of which
      rises between the veins puckered elevations convex on one
      side and concave on the other.

Source : WordNet®

bullate
     adj : of leaves; appearing puckered as if blistered