Callitriche brutia var. hamulata
Watsonia 26: 113. 2006.
Leaves connate at base, ± linear, tapering strongly from near base or spatulate, 5.4–18 × 0.3–3 mm, 1+-veined. Stem and leaf scales present. Inflorescences: bracts caducous. Pedicels 0 mm, rarely less than 2 mm in fruit. Flowers usually solitary; styles reflexed, appressed to ovary; pollen colorless. Schizocarps 1.1–1.5(–1.6) × 1.1–1.4 mm, as long as wide; mericarps blackish, not swollen, winged throughout, wings straight, 0.03–0.3 mm wide. 2n = 38.
Phenology: Flowering Jul–Sep.
Habitat: Fast-flowing streams, backwaters, lakes, pools.
Elevation: 0–1600 m.
Greenland, B.C., Oreg., Wash., Europe.
Variety hamulata is considered native in Greenland and is introduced in other parts of the flora area; the earliest specimen of var. hamulata known from western North America is from Oregon in 1956 (Steward 7238, MO).