Source : Webster's Revised Unabridged Dictionary (1913)

Perigynium \Per`i*gyn"i*um\, n.; pl. {Perigynia}. [NL. See
   {Perigynous}.] (Bot.)
   Some unusual appendage about the pistil, as the bottle-shaped
   body in the sedges, and the bristles or scales in some other
   genera of the Sedge family, or {Cyperace[ae]}.

Source : WordNet®

Cyperaceae
     n : bulrush; chufa; cotton grass; papyrus; umbrella plant [syn:
         {family Cyperaceae}, {sedge family}]