Ludwigia sphaerocarpa Elliott. Section: Isnardia. Phen: Jun-Sep. Hab: Boggy areas, pools, ditches, river marshes, interdune swales, river and pondshores, tidal freshwater marshes. Dist: E. MA south to n. FL, west to e. TX, primarily on the Coastal Plain, spottily distributed in that range, and also disjunct in w. NY, sc. TN, s. IN, and nw. IN, ne. and s. IL.
Origin/Endemic status: Native
Taxonomy Comments: This species is tetraploid (n = 16). Peng (1989) considers it likely that L. sphaerocarpa is of allopolyploid origin, one or both of its parents now extinct.
Other Comments: Recently rediscovered in Illinois in 2019 by Paul Marcum in Pope County, approximately 160 years after first being discovered in the state much further north in Cook County. This species otherwise primarily occurs in the coastal plain outside of its Great Lakes disjunction.
Synonymy: = C, Fl4, FNA10, GW2, K1, K3, K4, Mi, NE, NY, Pa, RAB, S, Tn, Va, WH3, Peng (1989), Wagner, Hoch, & Raven (2007); > Ludwigia sphaerocarpa Elliott var. deamii Fernald & Griscom – F, G, Il; > Ludwigia sphaerocarpa Elliott var. jungens Fernald & Griscom – F, G; > Ludwigia sphaerocarpa Elliott var. macrocarpa Fernald & Griscom – F, G; > Ludwigia sphaerocarpa Elliott var. sphaerocarpa – F, G