Proc. Acad. Nat. Sci. Philadelphia 98: 96. 1946.
Perennials. Stems prostrate, 15–30 cm, hairy. Leaves glabrous; blade base narrowly cuneate, margins crenate, apex rounded with a narrow petiole-like base. Pedicels 10–12 mm. Flowers: sepals 4(or 5), ovate to oblong, calyx radially symmetric; corolla white with yellow throat, 3–5 mm; stamens 3 or 4, didynamous.
Phenology: Flowering Aug–Oct.
Habitat: Shallow, quiescent water, lakes.
Elevation: 0–20 m.
Introduced; Ark., La., Central America (Costa Rica, Nicaragua), South America (Brazil), introduced also in w, c Africa (Republic of Cameroon, Democratic Republic of Congo, Ghana, Nigeria, Senegal).
Bacopa egensis was first collected in the United States by Josiah Hale in the early 1800s (C. E. Depoe 1969). There are subsequent collections from Arkansas and Louisiana.