1. Amethystea caerulea Linnaeus, Sp. Pl. 1: 21. 1753.
水棘针 shui ji zhen
Stems 30-100 cm tall, base sometimes woody, pyramidally branched, purplish, pilose or puberulent especially on nodes. Petiole 0.7-2 cm, purple or purplish green, grooved, narrowly winged, sparsely hirsute; leaf blade triangular to subovate, sometimes purplish, usually 3-5-partite, lobes lanceolate, adaxially puberulent to subglabrous, abaxially glabrous, margin coarsely serrate to double serrate; middle lobe 2.5-4.7 × 0.8-1.5 cm; lateral lobes 2-3.5 × 0.7-1.2 cm, asymmetrical, decurrent. Panicles composed of lax, long pedunculate cymes; peduncle sparsely glandular; bracteoles ca. 1 mm, ciliate. Pedicel 1-2.5 mm, sparsely glandular. Calyx ca. 2 mm, papillate outside, glandular, the 5 accessory veins inconspicuous; teeth triangular, ca. 1 mm, apically acuminate, ciliate. Corolla blue or purplish blue, tube glabrous; limb glandular, lobes of upper lip oblong-ovate to ovate, lower lip slightly larger. Nutlets abaxially netted-wrinkled, adaxially ribbed, smooth, areole ca. 1/2 as long as nutlet. Fl. Aug-Sep, fr. Sep-Oct.
Fields, sandy soil along rivers, open roadsides, streamsides; 200-3400 m. Anhui, Gansu, Hebei, Henan, Hubei, Jilin, Liaoning, Nei Mongol, Shaanxi, Shandong, Shanxi, Sichuan, Xinjiang, Xizang, Yunnan [Japan, Kazakhstan, Korea, Kyrgyzstan, Mongolia, Russia; SW Asia]
Used medicinally for perspiration.