Perennial submerged aquatic with stems to c. 60 cm long, often rooting at nodes. Leaves shortly petiolate; petiole bases dilated into membranous, often appressed-hairy sheaths; blades c. obovoid in vivo, 1–5 cm long and wide, repeatedly divided into filiform segments (at least the basal division trichotomous), ultimate segments c. 2–5 mm long. Flowers usually emergent on pedicels 2–5 cm long which are decurved in fruit; sepals ovate to obovate, 2–3.5 mm long, glabrous, often tinged purple, reflexed, soon deciduous; petals 4 or 5, obovate to cuneate, 3–7 mm long, entirely white or yellow at base; nectary minute, near base of petal, with a low crescentic ridge proximally; stamens 5–15. Achenes usually c. 20, obovate, lenticular, c. 1.5 mm long, prominently transversely ridged on sides; beak absent or to 0.2 mm long; receptacle hispid. Flowers Oct.–Feb.
LoM, MuM, Wim, GleP, VVP, VRiv, GipP, OtP, WaP, Gold, CVU, GGr, DunT, NIS, EGL, EGU, HSF, HNF, MonT, VAlp. Also SA, NSW, ACT, Tas. Widespread in clear, freshwater streams and lakes, chiefly in cooler parts of the State, but seldom very common.
