Hydrocotyle rivularis
H.Eichler ex HenwoodProstrate perennial with robust stems, rooting at nodes. Leaf-lamina divided to base into 3 segments, to 30 mm across; segments orbicular, (3–)6–11 mm long, (3–)7–15.5(–20) mm wide, the outer pair bilobed, apex obtuse or rounded, margins with rounded teeth, surfaces glabrous; petiole (10–)50–160 mm long, glabrous; stipules membranous and entire. Umbels simple, leaf-opposed, globose, 3–5 mm diam., 7–10-flowered; flowers pedicillate; flowering pedicels 1–1.8 mm long; peduncle (5–)30–50 mm long. Petals white, occasionally with purple margins. Fruits slightly compressed laterally, 0.9–1 mm long, 0.7–0.8 mm wide; mericarps with acute lateral and dorsal ribs, intermediate ones not raised. Flowers Dec.–Feb.
EGL, HNF, MonT, VAlp. Also NSW and ACT. Rare in Victoria where known from montane streams and regularly inundated swamps above 600 m altitude in the Nunniong Plateau-Mt Cobberas area, with an isolated lowland occurrence along the lower Snowy River near Orbost. Mostly growing as a submerged aquatic, occasionally exposed on stream margins or as swamps recede.
Mapping for this species is incomplete due to confusion of records with H. tripartita with which H. rivularis was included prior to its recognition in 2014.
Spinning