Description from Flora of China
Carex augustinowiczii subsp. soyaeensis (Kükenthal) T. V. Egorova; C. eleusinoides Turczaninow var. flaccidior F. Schmidt; C. flaccidior (F. Schmidt) Miyabe & Kudô; C. soyaeensis Kükenthal.
Rhizome shortly stoloniferous. Culms tufted, 30-50 cm tall, trigonous, slender, slightly scabrous, clothed at base with purple-brown bladeless sheaths disintegrating into fibers. Leaves green, slightly shorter than or equaling culm, blades 2-3 mm wide, soft. Lowest involucral bract leafy, sheathing, remaining ones setaceous. Spikes 3-5, ± distant; terminal spike male, cylindric, 1-1.7 cm; lateral spikes female, rarely few with male flowers at base, cylindric, 1.5-3.5 cm; lowest spike with short peduncle, others subsessile. Female glumes dark sanguineous or purple-red, pale green at middle, oblong, 2-2.8 mm, apex acuminate or obtuse. Utricles pale gray-green or yellow-green, longer than glume, ovate-lanceolate or oblong-lanceolate, obtusely trigonous, ca. 3 mm, finely many veined, base cuneate, apex gradually narrowed into a beak, orifice emarginate. Nutlets elliptic, trigonous, ca. 2 mm; style slender, base not thickened; stigmas 3.
Forests, riversides, sandy wet places. Hebei, Heilongjiang, Jilin, Liaoning [Japan, Russia (Far East)].