22. Hydrocotyle L. (water pennywort)

Plants perennial, with thin, fibrous roots, glabrous. Stems 5–30 (or more) cm long, prostrate, creeping, rooting at the nodes. Leaves solitary or occasionally appearing paired at the nodes, long-petiolate, glabrous. Leaf blades peltate or deeply cordate at the base, circular to broadly depressed-oval or broadly kidney-shaped, the margins scalloped and/or lobed. Inflorescences simple umbels or spikes, sometimes appearing headlike on smaller plants, axillary, the stalks shorter than the petioles. Bractlets 0.5–1.2 mm long, lanceolate to oblong-lanceolate. Sepals absent. Petals ovate, rounded or bluntly pointed at the tip, white. Ovaries glabrous. Fruits circular to depressed-circular in outline, rounded or truncate to shallowly cordate at the base and tip, strongly flattened laterally, glabrous, tan to brown, the mericarps with the ribs inconspicuous or the dorsal and lateral ribs somewhat corky-thickened. About 130 species, nearly worldwide.