Description from Flora of China
Persicaria excurrens (Steward) Koidzumi; P. viscofera (Makino) H. Gross ex Nakai; Polygonum excurrens Steward; P. makinoi Nakai.
Herbs annual. Stems 30-70 cm tall, usually branched above, pubescent. Petiole very short or nearly absent; leaf blade lanceolate or broadly lanceolate, both surfaces hispid, densely so along midvein, long ciliate at margin, base rounded or cuneate, apex acuminate; ocrea tubular, 6-12 mm, membranous, long hispid, apex ?truncate, long ciliate. Inflorescence spicate, lax, 4-7 cm, interrupted at base, several spikes aggregated and panicle-like; peduncle glabrous, sparsely viscid-glandular; bracts green, funnel-shaped, glabrous but ciliate, each 3-5-flowered. Pedicels longer than bracts. Perianth greenish, 5(or 4)-parted; tepals elliptic, 1-1.5 mm. Stamens 7 or 8, included. Styles 3, connate to below middle. Achenes included in persistent perianth, black-brown, shiny, ovoid, trigonous, ca. 1.5 mm, smooth. Fl. Jul-Sep. fr. Aug-Oct. 2n = 24.
This species shows considerable variation in leaf shape and pubescence. Plants with linear-lanceolate leaves and more or less glabrous stems and abaxial leaf surfaces are often recognized as a distinct variety, Polygonum viscoferum var. robustum Makino (Bot. Mag. (Tokyo) 17: 116. 1903; P. viscoferum subsp. robustum (Makino) Kitamura).
Moist valleys, mountain slopes; 500-1800 m. Anhui, Fujian, Guizhou, Hebei, Heilongjiang, Henan, Hubei, Hunan, Jiangsu, Jiangxi, Jilin, Liaoning, Shandong, Sichuan, Taiwan, Yunnan, Zhejiang [Japan, Korea, Russia (Far East)].