Biennial or short-lived perennial to 1.5 m, glabrous or nearly so throughout, or somewhat hairy in the infl, or the lvs minutely puberulent; lvs narrow, the basal narrowly oblanceolate, to 30 נ2 cm, the cauline varying to narrowly lanceolate or lance-elliptic, seldom over 15 נ1.5 cm; infls spicate and ±leafy-bracteate, the tip nodding; hypanthium 3.5-4.5 cm; sep 2-4 cm, the appendages 3-7 mm, subterminal as in no. 2 [Oenothera parviflora L.]; pet 2-4 cm; anthers 8-12 mm; style 2-3.5 cm; fr 2-3 cm, tapering upwards, half as thick at the top as at the base; seeds 1-1.5 mm, prismatic-angled; 2n=14. Shale-barrens; n. Pa. to w. Va. and e. W.Va. July-Sept.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.