The Collaborative International Dictionary of English v.0.48:

Pulu \Pu"lu\, n.
   A vegetable substance consisting of soft, elastic, yellowish
   brown chaff, gathered in the Hawaiian Islands from the young
   fronds of free ferns of the genus Cibotium, chiefly
   Cibotium Menziesii; -- used for stuffing mattresses,
   cushions, etc., and as an absorbent.
   [1913 Webster]