The Collaborative International Dictionary of English v.0.48:

Pullulate \Pul"lu*late\, v. i. [L. pullulatus, p. p. of
   pullulare to sprout, from pullulus a young animal, a sprout,
   dim. of pullus. See pullet.]
   To germinate; to bud; to multiply abundantly. --Warburton.
   [1913 Webster]

WordNet (r) 3.0 (2006):

pullulate
    v 1: be teeming, be abuzz; "The garden was swarming with bees";
         "The plaza is teeming with undercover policemen"; "her mind
         pullulated with worries" [syn: teem, pullulate,
         swarm]
    2: move in large numbers; "people were pouring out of the
       theater"; "beggars pullulated in the plaza" [syn: pour,
       swarm, stream, teem, pullulate]
    3: produce buds, branches, or germinate; "the potatoes sprouted"
       [syn: shoot, spud, germinate, pullulate, bourgeon,
       burgeon forth, sprout]
    4: become abundant; increase rapidly
    5: breed freely and abundantly