The Collaborative International Dictionary of English v.0.48:

Tetradynamian \Tet`ra*dy*na"mi*an\, n. (Bot.)
   A plant of the order Tetradynamia.
   [1913 Webster] Tetradynamian

The Collaborative International Dictionary of English v.0.48:

Tetradynamian \Tet`ra*dy*na"mi*an\, Tetradynamous
\Tet`ra*dyn"a*mous\, a. (Bot.)
   Belonging to the order Tetradynamia; having six stamens, four
   of which are uniformly longer than the others.
   [1913 Webster]