The Collaborative International Dictionary of English v.0.48:

Decagynian \Dec`a*gyn"i*an\ (d[e^]k`[.a]*j[i^]n"[i^]*an),
Deccagynous \Dec*cag"y*nous\, a. [Cf. F. d['e]cagyne.] (Bot.)
   Belonging to the Decagynia; having ten styles.
   [1913 Webster]