Carex wahuensis subsp. wahuensis is a species of rhizomatous perennials that form large, dense clumps with trigonous culms measuring (15–)40–100 cm in height, bearing spikes from the base upwards. The leaves are 3-ranked, with up to 8 per culm, featuring linear, flat blades (1.5–)5–8(–15) mm wide, coriaceous, with a gradually tapering, long-acuminate apex, deep green upper surfaces, scabrous lower surfaces on veins, and entire margins. The inflorescence consists of (2–)4–9(–14) nodose arrangements, with internodes 2–5 cm long, and each spike solitary at nodes, cylindrical, (0.8–)5–10 cm long and 5–15 mm wide, with the terminal spike staminate and lateral ones androgynous or pistillate; the pistillate glumes are brown, membranous, ovate, 2.5–5 mm long, with a scabrous awn 3–5 mm long, and the perigynium is chartaceous to subcoriaceous, ellipsoid to obovoid or broadly obovoid, (3–)5–8 mm long, 1–4 mm wide, many-veined, and obtusely trigonous in cross-section. The fruits are rhombic–ellipsoid achenes, trigonous, usually conspicuously constricted at angles. The seeds are one per achene seed coat thin, free from the pericarp, embryo basal, and endosperm abundant. It grows in a variety of habitats, including dry to mesic forests, mesic and subalpine shrublands, and sometimes mesic coastal forests, usually on ridges, slopes, or in gulches, often on rocky substrates, with an elevation range of (10–)250–2,500 m.