Trans. Amer. Philos. Soc., n. s. 5: 140. 1835.
Leaves connate at base, obovate-oblanceolate to spatulate, (2.2–)2.7–5.7 × 0.7–2 mm, 2+-veined. Stem and leaf scales present. Inflorescences: bracts absent. Pedicels 0–5 mm in fruit. Flowers usually 1 staminate and 1 pistillate in 1 axil opposed by 1 pistillate, rarely both pairs at an axil with 1 staminate and 1 pistillate; styles loosely ascending or ± reflexed; pollen yellow. Schizocarps 0.8–1 × 0.9–1.3 mm, shorter than wide; mericarps black, not swollen, winged throughout, wings curled, giving appearance of thickened margins, 0.06–0.15 mm wide. 2n = 20.
Phenology: Flowering Feb–Jun(Sep–Oct).
Habitat: Seasonally wet sandy soils, in or shaded by woodlands.
Elevation: 0–100 m.
Ala., La., Miss., Tex.
Callitriche nuttallii Torrey is an illegitimate, superfluous name that applies here. Torrey proposed it as a replacement for C. pedunculosa Nuttall based on the mistaken belief that the name by Nuttall was a later homonym of one by Arnott; the purported name by Arnott does not exist.