Bot. Mag. (Tokyo) 34: 39. 1920.
Plants perennial. Stems 0.75–1.5 m, glabrous or slightly pubescent. Leaf-blades ovate-elliptic, 2.5–13.5 × 0.2–6.8 cm, base tapering, apex acute to acuminate, pubescent on veins abaxially, short-pubescent adaxially, varying to glabrous or glabrescent. Inflorescences 2–4 cm in flower, elongating to 21 cm in fruit; bracteoles spinose; basal wings attached at base and sometimes slightly on sides. Flowers: tepals 5, 4–5 mm; pseudostaminodes with margins entire, denticulate, or slightly 2-lobed at apex. Utricles elliptic, 2.5 mm.
Phenology: Flowering summer.
Habitat: Wooded riverbanks
Elevation: 100-200 m
Introduced; Ky., Ohio, W.Va., Asia
The plants of Achyranthes japonica in our area evidently belong to var. hachijoensis Honda, which has glabrous or glabrescent leaves.
"elongating" is not a number.