The Collaborative International Dictionary of English v.0.48:
Achlamydeous \Ach`la*myd"e*ous\, a. (Bot.) Naked; having no floral envelope, neither calyx nor corolla. [1913 Webster]WordNet (r) 3.0 (2006):
achlamydeous adj 1: not having a floral envelope or perianth [ant: chlamydeous]