Rotala taiwaniana Y. C. Liu & F. Y. Lu

This species is known only from the type (F. Y. Lu & C. H. Ou 5511, holotype NCUF, isotype TPCA).

Herbs, annual, terrestrial or amphibious, 15-20 cm. Stem procumbent at base; branches ascending, weakly 4-angled. Leaves decussate, obovate-oblong, 1.8-2.6 × 0.2-0.4 cm, base attenuate, apex acute or subacute. Bracts narrowly lanceolate, 6-7 mm. Flowers 4-merous, solitary, sessile, axillary on main stem and branches; bracteoles undescribed. Floral tube tubular-campanulate, ca. 3 mm; sepals 4, narrowly deltate; epicalyx segments deltate, ca. 1/2 as long as sepals. Petals 4, whitish, equaling sepals. Stamens 4; anthers included. Ovary obovoid; style ca. 0.4 mm. Capsules ovoid, tuberculate, included in floral tube. Seeds semiovate, pale brown. Fl. undescribed, fr. Dec.

● Drained paddy fields, wet places. E Taiwan (Hualian).