Erect perennial 4-10 dm from a cluster of fleshy-fibrous roots; stem spreading-hirsute; lvs alternate, erect or ascending, lanceolate or lance-linear, obtuse or acutish, 2-5 cm, rounded at the sessile base, densely pubescent on both sides; pedicels 3-8 mm, bracteolate near the top; fls 4-merous; pet 10-15 mm, exceeding the erect to spreading sep; fr spreading-hirsute, equaling or shorter than the pedicel, otherwise as in no. 5 [Ludwigia alternifolia L.] Swamps on the coastal plain; s. N.J. to Fla., Ark., and Tex. June-Sept.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.