Fr broadly cupulate, 3-4 mm, sharply 4-angled or narrowly 4-winged; 2n=48; otherwise much like no. 8 [Ludwigia polycarpa Short & Peter]. Swamps and bogs on the coastal plain; se. Va. to Fla. and Miss. July-Nov.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.