The Collaborative International Dictionary
Cassideous
Cassideous \Cas*sid"e*ous\, a. [L. Cassis helmet.] (Bot.) Helmet-shaped; -- applied to a corolla having a broad, helmet-shaped upper petal, as in aconite.
Wiktionary
cassideous
a. (context botany English) Shaped like a helmet; applied to a corolla with a broad, helmet-shaped upper petal, as in aconite.