16. Polygonum rigidum Skvortsov in Baranov & Skvortsov, Diagn. Pl. Nov. Mandsh. 5. 1943.
尖果萹蓄 jian guo bian xu
Herbs annual. Stems erect or ascending, 30-50 cm tall, much branched, angulate. Petiole short, articulate at base; leaf blade elliptic or oblong, 1-3 cm × 3-7 mm, both surfaces with conspicuous veins, base cuneate, margin entire, apex obtuse or subacute; ocrea: lower part brown, upper part white, 5-9-veined, lacerate. Flowers 2-7 in axillary fascicles. Pedicel 1.5-2 mm, apex articulate. Perianth green, margin white or pinkish, 5-parted to 2/3; tepals oblong, 2-2.5 mm. Stamens 8; filaments dilated at base. Styles 3, short. Achenes exserted from persistent perianth, brown, slightly shiny, ovoid, trigonous, 2.5-3.5 mm, densely minutely punctate, apex long acute. Fl. Jun-Aug, fr. Jul-Sep. 2n = ca. 60.
Near fields, roadsides, shaded grassy places in valleys; 400-2500 m. Gansu, Hebei, Heilongjiang, Jilin, Liaoning, Nei Mongol, Shaanxi, Shanxi [Mongolia, Russia].