Annuals mat-forming. Leaves clustered or scattered along stolons; blade linear to filiform, 1–3.5 × 0.1–0.2 cm, young leaves with tapering sheaths at base. Pedicels recurved in fruit, 1–2 cm. Flowers: calyx not purple spotted, lobes 0.5–1 mm, tube 1–2 mm; corolla white to pale lavender, 2–4 mm, lobes rounded; stamens attached at same level; style 1 mm, capitate. Capsules globular, 2–3 mm. 2n = 20.
Phenology: Flowering May–Aug(–Oct).
Habitat: Muddy or sandy pond or stream margins, often in brackish water.
Elevation: 0–10 m.
St. Pierre and Miquelon, N.B., Nfld. and Labr., N.S., P.E.I., Que., Conn., Del., Maine, Md., Mass., N.H., N.J., N.Y., N.C., Pa., R.I., Va., South America, Africa, Pacific Islands (New Zealand), Australia.
In the flora area, Limosella australis is native to eastern North America and is rare in much of its range. Reports of L. australis from California are likely based on misidentified material.