The Collaborative International Dictionary of English v.0.48:

Phloem \Phlo"["e]m\, n. [Gr. ? bark.] (Bot.)
   That portion of fibrovascular bundles which corresponds to
   the inner bark; the liber tissue; -- distinguished from
   xylem.
   [1913 Webster]

WordNet (r) 3.0 (2006):

phloem
    n 1: (botany) tissue that conducts synthesized food substances
         (e.g., from leaves) to parts where needed; consists
         primarily of sieve tubes [syn: phloem, bast]