1. Coldenia procumbens Linnaeus, Sp. Pl. 1: 125. 1753.
双柱紫草 shuang zhu zi cao
Herbs annual. Stems branched from base; branches prostrate or ascending, 15-40 cm, densely spreading strigose. Lower stem leaves short petiolate, oblong to obovate, 1-2 × 0.5-1.5 cm, asymmetrical, scabrous, strigose, margin coarsely crenate-lobulate; lateral veins 4-6 pairs, prominent abaxially, concave adaxially; upper leaves sessile. Flowers solitary, subsessile. Calyx 1.5-2 mm; lobes lanceolate to ovate-lanceolate, slightly enlarged in fruit, persistent, strigose. Corolla white, tubular, 2-2.5 mm, glabrous; lobes orbicular, ca. 0.3 mm. Stamens included; filaments ca. 0.3 mm, glabrous, inserted at middle of corolla tube; anthers rounded to broadly ovate, ca. 0.2 mm. Ovary fastigiate, 4-sulcate; stigma obscurely 2-cleft. Fruit broadly triangular, 3-4 mm, glandular pubescent; mericarps wrinkled, spinescent-tuberculate. Fl. Apr, fr. Jun.
Sandy places, beaches, dry cultivated ground. Hainan, Taiwan [Cambodia, India, Indonesia, Malaysia, Pakistan, Sri Lanka, Thailand, Vietnam; Africa, Australia, North America, South America].