Perennial herb 30 cm - 1 m tall Leaves: opposite, spreading, stalkless (sometimes clasping), hairless, very finely-toothed, three- to seven-nerved, yellow-green, 5 - 15 cm long, 1.5 - 5 cm wide, lance- to egg-shaped, widest near the broadly rounded base, and gradually tapering to a long, pointed tip. Inflorescence: of many (one to twenty), stalkless, compactly clustered flowers at the stem apex, or also in smaller clusters in the upper one or two leaf axils. The terminal inflorescence is subtended by two or three pairs of large, leaf-like bracts. Flowers: yellow-white or green-white, 3 - 5.5 cm long, radially symmetric, somewhat oblong-tubular, with a narrowly opened top, and green-veined, pleated sides. Sepals: five, but fused for over half their length into a whitened, 0.7 - 1.5 cm long, hairless tube, then separating into yellow-green, 0.4 - 1.5 cm long, 3 - 7 mm wide, spreading-ascending, hairless, very finely-toothed, somewhat egg-shaped lobes, which have a ridge-like structure (keel) running down their outer face onto the fused tube portion. Petals: five, but fused with shorter membranes (plaits) between the erect, 4 - 7 mm long, 4 - 8 mm wide, broadly egg-shaped to rounded, somewhat inrolled petal lobes. The separate portion of the petal lobes reaches 4 - 6 mm beyond the 0.5 - 4 mm long, 3 - 7 mm wide, jagged-toothed, angled plaits. Stamens: five, attached to the inside of the petal tube, the filaments 0.8 - 1.2 cm long, with the anthers fused together. Pistil: with a single-chambered, superior ovary; a short, stout style; and a two-lobed stigma. There is a whorl of nectar glands present around the base of the ovary, though they are not attached to the fused petal tube base. Fruit: a single-chambered, two-valved, elliptic capsule containing numerous seeds. Stems: one to ten, erect, stout, hairless, and normally unbranched. Seeds: flattened, winged, and smooth.
Similar species: This is the only whitish-flowered gentian in our area except for the rare albino of other species. Albino forms of Gentiana andrewsii or its varieties differ by having rough-prickly leaf edges, hairy sepal lobe edges, and plaits longer than the alternating petal lobes. Albino forms of G. puberulenta may also be similar, but they have a hairy stem, very narrow sepal lobes, open flowers, and separate anthers.
Flowering: August to October
Habitat and ecology: Uncommon overall, found in moist prairies, sometimes swales, or other wet or moist clearings.
Occurence in the Chicago region: native
Etymology: Gentiana is named after Gentius, king of Illyria, who supposedly discovered a medicinal value for the yellow gentian. Alba is the Latin word for white, which refers to the whitish flowers.
Stout, 3-10 dm, almost always unbranched; herbage glabrous; lvs yellow-green, spreading, lanceolate or lance-ovate, 5-15 נ1.5-5 cm, long-acuminate, widest near the broadly rounded or subcordate sessile base, often 3-nerved; infl usually compact and many-fld; cal-lobes lance-ovate to deltoid-ovate, 4-15 mm, often spreading, with a prominent keel decurrent onto the tube; cor yellowish-white or greenish-white, 3.5-5 cm, narrowly open, its broadly ovate lobes commonly 4-6 mm longer than the oblique, ±erose plaits; anthers connate. Moist prairies and open woods; irregularly from s. Ont. to Pa. and N.C., w. to Minn., e. Neb., e. Kans., and n. Ark., more abundant westward. Sept., Oct. (G. alba Muhl., nomen subnudum)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.