Description from Flora of China
Commelina japonica Thunberg, Trans. Linn. Soc. London 2: 332. 1794; Aneilema herbaceum (Roxburgh) Wallich ex C. B. Clarke; C. elata Vahl; C. herbacea Roxburgh; C. lineolata Blume; Murdannia elata (Vahl) Brückner.
Herbs perennial. Roots fibrous, ca. 2 mm in diam., slightly fusiform thickened, densely or rarely sparsely tomentose. Rhizomes absent. Main stem undeveloped and very short; fertile stems arising from base of main stems, erect, 20--40 cm × ca. 3 mm, glabrous or hispidulous near nodes. Leaves on main stems several, basal, rosulate; leaf blade narrowly elliptic, 8--15 × (1.5--)2--4.5 cm, glabrous, base cuneate or broadly cuneate, margin undulate, apex obtuse, acute, or shortly acuminate. Leaves on fertile stems several, cauline; basal leaf sheathlike, membranous, bladeless, 2-lobed, lobes subulate-triangular; other leaves with blade similar to that of rosulate leaves but wider, hirsute only on sheath, undulate at margin. Panicles terminal, consisting of several cincinni, glabrous throughout; cincinni to 3 cm, with several flowers, 2 to several fertile; involucral bracts small, proximal ones longest, ca. 1.5 cm, distal ones ca. 3 mm, membranous; bracts extremely small, membranous, enveloping cincinnus axis; pedicels straight, very short at anthesis, to 7 mm in fruit. Sepals narrowly elliptic, 0.5--6 mm, persistent. Petals purple or blue, obovate-orbicular. Fertile stamens 2 or 3; filaments pubescent; staminodes 3; antherodes 3-sect. Capsule broadly ellipsoid, trigonous, ca. 5 × 4 mm, obtuse at both ends. Seeds 2--4 per valve, uniseriate, brown-gray, tetragonal, 3 sides flat, 1 slightly convex and verrucose. Fl. May--Jul, fr. Aug--Sep.
Humid forests, forest margins, thickets; 1400--2000 m. S Yunnan [Bhutan, India, Indonesia, Japan, Laos, Malaysia, Myanmar, Sikkim, Thailand].