Kneiffia allenii Small; K. arenicola Small; K. brevistipata Pennell; K. charlesii Lahman; K. fruticosa (Linnaeus) Spach ex Raimann var. humifusa (Allen) Pennell; K. fruticosa var. unguiculata (Fernald) Moldenke; K. linearis (Michaux) Spach; K. longipedicellata Small; K. semiglandulosa Pennell; K. subglobosa Small; K. tetragona (Roth) Pennell var. longistipata Pennell; K. velutina Pennell; O. fruticosa var. eamesii (B. L. Robinson) S. F. Blake; O. fruticosa var. goodmanii Munz; O. fruticosa var. humifusa Allen; O. fruticosa var. linearifolia Hooker; O. fruticosa var. linearis (Michaux) S. Watson; O. fruticosa var. microcarpa Fernald; O. fruticosa var. subglobosa (Small) Munz; O. fruticosa var. unguiculata Fernald; O. fruticosa var. vera Hooker; O. linearis Michaux; O. linearis var. eamesii B. L. Robinson; O. longipedicellata (Small) B. L. Robinson; O. subglobosa (Small) Weatherby & Griscom; O. subglobosa var. arenicola (Small) Weatherby & Griscom; O. tetragona Roth var. brevistipata (Pennell) Munz; O. tetragona var. longistipata (Pennell) Munz; O. tetragona var. sharpii Munz; O. tetragona var. velutina (Pennell) Munz; O. unguiculata (Fernald) Sorrie, LaBlond & Weakley

Herbs moderately to densely strigillose, and/or some­times glandular puberulent or villous; from fibrous or, sometimes, slightly fleshy rootstock or producing rhizomes. Leaves: basal 3–10 × 0.5–2 cm, petiole 1–4 cm, blade oblanceolate to obovate, margins subentire or weakly and remotely denticulate; cauline 2–6(–8) × 0.1–1(–1.7) cm, petiole 0.2–2(–4) cm, blade linear, lanceolate to oblanceolate, narrowly elliptic, or nar­rowly ovate, margins subentire or weakly and remotely denticulate. Flowers: buds with free tips 0.5–1(–6) mm, usually connivent, sometimes spreading; floral tube5–15 mm; sepals 5–20 mm; petals (8–)15–25 mm. Capsules clavate to oblong-clavate, widest distal to middle, angled, rarely narrowly winged, (5–)10–17(–20) × (2–)3–4 mm, stipe 3–10 mm; sessile. 2n = 28, 42.

Flowering Apr–Aug(–Sep). Open habitats, meadows, stream margins, edges of woods, open woods, margins of freshwater or saltwater marshes, stabilized sand dunes, roadsides, partially disturbed habitats; 0–500(–1100) m; Ala., Ark., Conn., Del., D.C., Fla., Ga., Ill., Ind., Ky., La., Md., Mass., Miss., Mo., N.Y., N.C., Ohio, Okla., Pa., S.C., Tenn., Va., W.Va.

Kneiffia suffruticosa Spach (1835) is an illegitimate substitution for Oenothera fruticosa, as is K. angustifolia Spach (1835) one for O. linearis Michaux, and O. linearis var. allenii Britton (1894) is one based on O. fruticosa var. humifusa.