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.
Fibrous-rooted annual; stems at first erect, later diffuse and rooting from the lower nodes, to 8 dm; lf-blades lance-ovate, the larger 5–12 × 1.5–4 cm; sheaths 1–2 cm; spathe (folded) broadly semicordate, 1.5–3 cm, half as wide, acute or short-acuminate, glabrous or minutely hairy, basally with dark green veins on a paler background, its margins free, its stalk 1–7 cm; blade of upper pet 8–15 mm; lower median pet white or nearly so; anthers 6 (3 sterile); ovary 3-locular; fr 2-locular and 4-seeded, the upper locule of the ovary abortive; 2n=36–90. Moist or shaded ground, often a garden-weed; native of e. Asia, intr. from N.H. to Ga., w. to N.D. and Tex. Several forms, often locally constant, differing in details of pubescence, size and intensity of color of pet, and color of sterile stamens.
An annual herb with creeping stems. It grows 20-60 cm high. It can produce many branches that root at the nodes. The leaves are sword shaped and 4-9 cm long by 2 cm wide. It forms a sheath around the stem at the base. The flowers are bright blue. The 3 petals are not equal in size. There are 2 large ones and one small one. The upper 2 are blue and the lower one is white.