The Collaborative International Dictionary of English v.0.48:

Pycnidium \Pyc*nid"i*um\, n.; pl. Pycnidia. [NL., fr. Gr. ?
   crowded.] (Bot.)
   In certain fungi, a flask-shaped cavity from the surface of
   the inner walls of which spores are produced.
   [1913 Webster]

WordNet (r) 3.0 (2006):

pycnidium
    n 1: flask-shaped asexual structure containing conidia