15. Isopyrum Linnaeus, Sp. Pl. 1: 557. 1753.
扁果草属 bian guo cao shu
Fu Dezhi; Orbélia R. Robinson
Herbs perennial. Stem erect, smooth, glabrous. Leaves 2 × ternately compound. Basal leaves abaxially pale green, adaxially green. Stem leaves shortly petiolate; petiole sheathed; sheath white, membranous. Inflorescences panicled or cymose; bracts 1 or 2 × ternately compound, 3-lobed, or 3-sect. Flowers radially symmetric, small. Pedicel slender. Sepals 5, white, petaloid. Petals 5, much smaller than sepals, basally tubulose or shallowly scrotiform and shortly clawed. Stamens 20--30; filaments sublinear, 1-veined; anthers yellow, broadly ellipsoid. Pistils 1--5, free, erect, narrowly ovate; ovules numerous, arranged in 2 rows on ventral suture. Follicles 1--5, ellipsoid-ovoid, flat, horizontally veined, apically with a curved beak. Seeds numerous, black to blackish, ovoid to ellipsoid, smooth.
Four species: Asia, Europe, North America; two species (one endemic) in China.