Description from Flora of China
Pleurogyne Eschscholtz ex Chamisso & Schlechtendal; Swertia subgen. Lomatogonium (A. Braun) Satake; Pleurogynella Ikonnikov.
Herbs annual or perennial. Roots fibrous or woody; primary root with few secondary rootlets or rhizomes and with few fleshy adventitious rootlets. Stems prostrate, ascending, or erect, striate or angled, branched or simple. Inflorescences few- to many-flowered, terminal and axillary cymes, sometimes flowers solitary and terminal. Flowers (4- or) 5 (or 10)-merous. Pedicel usually longer than flower. Calyx and corolla rotate, lobed nearly to base or with a distinct tube. Corolla lobes dextrorse in flower bud, distinctly 2colored when corolla opens. Nectaries 2, at base of corolla lobes. Stamens inserted at base of corolla tube; filaments somewhat flattened; anthers blue, rarely yellow, shorter than or rarely as long as filaments. Ovary ensiform, cylindric, or ovoid-ellipsoid. Style absent; stigma lobes ± decurrent along carpel sutures. Capsules 2valved, many seeded. Seed coat almost smooth.
Eighteen species: North America, temperate Asia, Europe; 16 species in China.