Monochoria valida Wang & Nagamasu.

Herbs perennial, aquatic. Vegetative stems rhizomatous. Radical leaves with sheath broadened at base; petiole 0.4--1.7 m; leaf blade 10--35 × 1--15 cm, base sagittate to hastate with basal lobes to 11 cm, apex acuminate. Flowering stems erect, to 2 m; leaf petiole 4--18 cm; spathe ca. 4.5 cm. Inflorescences remaining erect after anthesis, racemose, 20--110-flowered; peduncle longer than associated leaf petiole. Pedicels to 3 cm. Perianth segments purplish blue, ca. 1.6 cm. Larger stamen: anther 6--10 mm. Smaller stamens: filaments filiform; anthers 3.5--6 mm. Style subequaling longest stamen. Capsule oblong, ca. 1.2 cm. Seeds brown, ovoid, 0.7--0.8 mm; wings ca. 10. Fl. Aug, fr. Mar.

Pools, rice fields, ditches. S China [Malaysia, Myanmar, Thailand].