Source : Webster's Revised Unabridged Dictionary (1913)

Vernation \Ver*na"tion\, n. [F. vernation: cf. L. vernatio the
   sloughing of the skin of snakes.] (Bot.)
   The arrangement of the leaves within the leaf bud, as regards
   their folding, coiling, rolling, etc.; prefoliation.

Source : WordNet®

vernation
     n : (botany) the arrangement of young leaves in a leaf bud
         before it opens