西南水马齿 xi nan shui ma chi

Plants submerged, with floating rosettes, on wet mud or creeping through and over other plants. Petiole 1.1-5.2 mm; leaf blade spatulate and very broadly expanded, 2.5-9.9(-10) × 0.4-6.7 mm; venation complex, characterized by primary and secondary veins, plus additional loops and anastomosing veins both within and outside secondary veins. Flowers solitary in leaf axils; bracts persistent, sexually dimorphic, those subtending carpellate flowers ca. 0.3 mm and staminate flowers 0.5-1.2 mm; styles shorter than 1.5 mm, persistent, erect to spreading when young, reflexed on mature fruit; filaments shorter than 2 mm, ± erect; anthers ca. 0.5 × 0.6 mm; pollen ovoid-ellipsoid, yellow, 18-21 × 16-20 µm. Fruit 1.3-1.5 × 1.6-1.9 mm, wider than high, dark with paler wing, subsessile or on pedicel shorter than 0.8 mm, broadly winged all round; wing 0.2-0.4 mm at top, 0.2-0.4 mm at side. Fr. Apr-Oct.

Pools, ditches, springs; 1100-3000 m. SE Xizang, C and W Yunnan [Bhutan, India, Indonesia (Sulawesi), Thailand].