Myriophyllum exasperatum D. Wang, D. Yu & Z. Y. Li

Plants hermaphroditic. Stem sparsely branched, reddish brown, 60-135 cm, rooting only at base, upper part usually emergent. Submerged leaves (4 or)5- or 6-whorled, pectinate, broadly ovate to suborbicular in outline, 4.5-5.5(-6) × 4-4.5 cm; segments 2.2-2.8 cm, filiform; emergent leaves smaller, uppermost ones alternate to pseudowhorled, undivided, linear to spatulate, margin toothed distally. Inflorescence a terminal spike of (4 or)5- or 6-whorled flowers, 13-31 cm; bracts spatulate; bracteoles slightly brown, broadly lanceolate to ovate. Flowers 4-merous. Sepals orbicular. Petals white, pinkish at apex, hooded, 1.5-1.8 × 0.5-0.8 mm, caducous. Stamens 8. Stigmas pinkish to white after anthesis, shortly fimbriate. Fruit reddish brown to olive brown, cubic, 1.8-1.9 × 1.9-2 mm; mericarps separating late, finely tuberculate, longitudinal abaxial ridge tuberculate. Fl. Aug-Nov, fr. Oct-Dec.

S Guangxi (Dongxing).

● Slow-flowing rivers and streams, stagnant waters; near sea level to 200 m.