Eriodendron anfractuosum

from The Collaborative International Dictionary of English v.0.48

Kapok \Ka*pok"\, n. [Prob. fr. the native name.] (Bot.)
   A silky wool derived from the seeds of {Ceiba pentandra}
   (syn. {Eriodendron anfractuosum}), a bombaceous tree of the
   East and West Indies.
   [Webster 1913 Suppl.]