Rotala filiformis (Bellardi) Hiern

Amphibious or aquatic annual or perhaps sometimes a perennial 5–40 cm. tall; stems red or brownish, erect, simple or irregularly branched, sometimes spongy and creeping beneath, often densely tufted and leafless beneath.. Leaves sometimes red, mainly 1-nerved, decussate; submerged leaves linear to lanceolate, 0.3–2 cm. long, 0.3–0.8(–3) mm. wide; aerial leaves lanceolate to ovate, (2–)5–9 mm. long, 1–7 mm. wide, obtuse to emarginate at the apex, truncate to cordate at the base; petiole absent or very short.. Flowers solitary in the axils, sessile or subsessile; bracteoles 2, linear-subulate, 0.2–1 mm. long.. Calyx pink; tube cupular, 1–1.5 mm. long, somewhat accrescent; lobes 4, triangular, equal or unequal, 0.5–0.7 mm. long; appendages absent.. Petals white or pale pink, 2–4 or sometimes missing, linear to obovate or round, up to 0.75 mm. long, 0.25 mm. wide.. Stamens (1–)2(–3–4); filaments 0.5 mm. long, the red-brown anthers included, borne below the stigma.. Ovary ± reddish, globose or ellipsoid, ± 0.8 mm. long; style 0.25–0.5 mm. long; stigma capitate.. Capsule red-brown, ellipsoid to obovoid or globose, 2mm. long, as long as or ± exceeding the calyx-lobes, 2-valved.. Seeds brownish, semi-ellipsoid, 0.3–0.4 mm. long.. Fig. 15/32–35, p. 53.