Key to species of Ludwigia with pubescent stems, alternate leaves, 4 sepals, 0 petals, and +/- sessile capsules ca. 1-1.5x as long as broad*

1. Flowers borne in compact, head-like or spike-like inflorescences, these lacking well-developed leaves...L. suffruticosa (Shrubby Seedbox)

1'. Flowers borne in the axils of well-developed leaves...2.

2. Sepals reflexed, adaxial surface white or creamy, tinged with pink (color best determined prior to fruiting); stem pubescence spreading; cells of seed surface suborbicular; style 1-2 mm long...L. pilosa (Hairy Seedbox)

2'. Sepals ascending, adaxial surface greenish, yellowish, or yellow-green (color best determined prior to fruiting); stem pubescence spreading or strigillose; cells of seed surface elongate; style 0.25-1 (1.25) mm long...3.

3. Stems hirtellous (pubescence spreading); sepals greenish on the upper surface (transitioning to red or brownish in fruit); bracteoles borne at or near the base of the capsule; capsule spreading-pubescent; seed surface cells elongate transverse to the seed length; style 0.25-0.5 mm long...L. ravenii (Raven's Seedbox)

3'. Stems strigillose; sepals yellowish or yellow-green on the upper surface; bracteoles usually borne on the short pedicel; capsule strigillose to glabrate; seed surface cells in patches with some cells elongate parallel to the seed length, others transverse to the seed length, and others diagonal; style 0.55-1 (1.25) mm long...L. sphaerocarpa (Globe-fruited Seedbox)

*Key, habitats, distributions, and phenology modified from Weakley (2015)