Apetalous

Apetalous ('without petals'), a term applied somewhat indefinitely to those flowering plants in which the petals are absent. It represented a distinct subdivision in A. de Jussieu's classification, Apetalæ—broadly corresponding to Monochlamydæ (q.v.) of later authors, but is more convenient as a merely descriptive term, since the absence of petals occurs not only in entire groups, like the catkin-bearing Amentacæ, but in degenerate forms in many unrelated orders. When both calyx and corolla are absent, the term achlamydeous (Gr. chlamys, 'a covering') is often used.