The Collaborative International Dictionary of English v.0.48:

Icosandria \I`co*san"dri*a\, n. pl. [NL., fr. Gr. ? twenty +?,
   ?, man, male: cf. F. icosandrie.] (Bot.)
   A Linn[ae]an class of plants, having twenty or more stamens
   inserted in the calyx. Icosandrian