Gentianeae
A large order of annual or perennial herbs, rarely shrubs. Flowers red, yellow, blue, white, or violet, showy, regular; calyx divided, persistent; corolla persistent, imbricate or induplicate, and often twisted in aestivation; stamens alternate with the lobes of the corolla. The leaves (alternate and trifoliolate in Meny-anthes) are nearly always opposite (rarely whorled), entire, exstipulate, usually ribbed. There are about forty-nine genera, and 520 species, broadly dispersed through almost all parts of the world; some are found at high elevations, and others in hot tropical plains. Bitterness characterises the whole order. Illustrative genera are: Chironia, Chlora, Erythraea, Gentiana, Limnanthemum, Lisianthus, Menyanthes, and Villarsia.