nychthemeron (nikthemeron)

[ Nychthemerus (nik-theme-rus), n. [NL., also improp. Nycthemerus; Nyc tag in aceæ (nik-taj-i-nā sē-ē), n. pl. [NL. (Lindley, 1835), as Nyc tagine a. Nyc tagineæ (nik-ta-jin'ē-ē), n. pl. [NL. (A. P. de Candolle, 1805), order of dicotyledonous apetalous plants of the series Curvembryeæ, characterized by the persistent perianth-base closing about the fruit as an outer pericarp. About 215 species are known, of 3 tribes and 23 genera, of which Mirabilis, the four-o'clock, is the type. They are usually herbs with undivided undivided leaves, and flowers in flat-topped clusters, often with a spongy bark and an involucre imitating a calyx.