Description from Flora of China
Carex dayunshanensis L. K. Ling & Y. Z. Huang; C. exerta K. L. Chu; C. ferruspiculata K. L. Chu; C. mandarinorum Raymond.
Rhizome rather stout and elongate. Flowering and vegetative culms spaced; sub-basal sheaths of flowering culms bladeless; blades of vegetative culms leathery to papery, broadly linear, 20-40 × 1-2.5 cm, glabrous or pilose on veins of both surfaces or abaxially, midvein and 2 lateral veins prominent. Flowering culms 30-40 cm tall, with spikes at nodes of upper 2/3 of culm; involucral bract sheaths inflated above and spathelike, glabrous or shortly pilose, blades much shorter to ca. 1/2 length of sheath, ligule indistinct. Spikes androgynous, single to 5-nate at each node, linear-cylindric, 2-3 cm, pedunculate; peduncle 2-15 cm, slender, often exserted; male part 1/4-1/2 length of spike, mostly distinctly shorter than female part, rather densely flowered; female part with 8-15 flowers, utricles sparse at maturity. Female glumes pale brown, ovate-elliptic, ca. 2.5 mm, rusty punctate, midvein distinct, many lateral veins indistinct, apex obtuse. Utricles slightly longer than glume, ovate-elliptic, trigonous, ca. 3 mm, prominently many veined, apex abruptly contracted into a short beak, beak bent downward, 1/8-1/4 length of utricle, subtruncate at orifice. Nutlet tightly enveloped, elliptic, trigonous, ca. 2.5 mm; style base not thickened; stigmas 3. Fl. and fr. May-Jul.
● Wet and shady places in forests; 800-1500 m. Anhui, Fujian, Guangdong, Guangxi, Hunan, Jiangxi, Zhejiang.