2. Commelina communis Linnaeus, Sp. Pl. 1: 40. 1753.
鸭跖草 ya zhi cao
Commelina coreana H. Léveillé & Vaniot.
Herbs annual. Stems creeping, diffuse, numerous branched, to more than 1 m, glabrous proximally, puberulent distally. Leaf sheaths glabrous; leaf blade lanceolate to ovate-lanceolate, 3--9 × 1.5--2 cm, glabrous. Involucral bracts borne opposite leaves, with 1.5--4 cm long stalk, cordate, folded, 1.2--2.5 cm, often hirsute-ciliate, apex acute. Proximal branch of cincinni with peduncle ca. 8 mm and 1 or 2 male flowers, distal branch with short peduncle and 3 or 4 bisexual flowers, nearly included in involucral bracts; pedicels ca. 3 mm at anthesis, curved and less than 6 mm in fruit. Sepals ca. 5 mm, membranous. Petals dark blue, 9--10 mm except proximal one ca. 5 mm. Capsule ellipsoid, 5--7 mm, 2-valved. Seeds 2 per valve, brown-yellow, semiellipsoid, 2--3 mm, flat on 1 surface, irregularly pitted, truncate at 1 end.
Humid places. Throughout China except for Qinghai, Xinjiang, and Xizang. [Cambodia, Japan, Korea, Laos, ?Malaysia, Russia (Far East), Thailand, Vietnam].
A medicinal herb with febrifugal, anti-inflammatory, and diuretic effects; also used for relieving sore throat and tonsilitis.