Sp. Pl. 1: 339. 1753.
Rhizomes 0.5–2 × 0.5–1.8 cm; bulbs 0.6–2.5 cm. Stems 1/4–1/3 floriferous, 0.6–2 m. Leaf blades linear, long-attenuate, 30–80 × 0.6–3.2 cm, apex acute. Inflorescences 1.3–8 dm; terminal raceme 1–2.6 dm; secondary racemes spreading to ascending, 0.2–1.1(–2.2) dm; tertiary racemes infrequent; bracts obovate to subulate, green to brown, 2–4(–6) mm, densely floccose abaxially and marginally. Tepals greenish yellow, aging dark reddish purple, ovate to obovate-oblong, 5.5–13 × 2.2–6 mm, base abruptly auriculate to hastate, clawed, margins entire, apex acute, claws 0.5–1.2(–2.5) mm; glands yellowish green, oblong to oblong-ovate, nectariferous; stamens 6.5–8.5 mm; filaments inserted at or above middle of claw, 0.7–2.5 mm from ovary base, not basally dilated, equaling tepal width at insertion point; anthers 0.9 mm; ovary ovoid, glabrous or pubescent; styles 1.5–3.5 mm; pedicel spreading to ascending, 5–20 mm. Capsules elliptic-ovoid, 10–18 × 6–10 mm, glabrous or glabrate. Seeds 5–8 × 2.5–4 mm (including wings). 2n = 16.
Phenology: Flowering late spring–summer.
Habitat: Bogs, marshes, wet woods, savannas, meadows, along railroads
Elevation: 10–800 m
Ala., Ark., Del., D.C., Fla., Ga., Ill., Ind., Iowa, Kans., Ky., La., Md., Miss., Mo., N.J., N.Y., N.C., Ohio, Okla., Pa., S.C., Tenn., Tex., Va., W.Va.
The clawed tepals of Melanthium virginicum distinguish it from M. parviflorum and M. woodii, which have tepals with gradually attenuate bases.