Cyperus hillebrandii var. hillebrandii is a perennial species distinguished by its short, sometimes slightly thickened rhizomes adorned with brown or reddish-brown basal sheaths and their fibrous remnants. The culms of this plant can reach a height of 15–60(–90) cm and are 2–6 mm in diameter near the base, featuring a trigonous and smooth texture. The leaves are simple and linear, with a stiffness that can vary in length, either shorter than or exceeding the culm, and are 3–12 mm wide. The lower sheaths of the leaves may exhibit a reddish-brown hue, and like many in its family, it lacks stipules. Floral characteristics include umbelliform inflorescences that are either simple or compound, appearing dense to lax, spanning 2–5 cm in length and 3–12 cm in width. The inflorescence comprises 6–8 rays, each 1–4 cm long, with solitary spikes accompanied by 1–3 lateral spikes. These spikes are cylindrical to oblong-cylindrical, 2–4 cm long, and 8–10 mm wide, densely populated with numerous spikelets. Involucral bracts number between 4–8, with the lower ones surpassing the length of the inflorescence, sometimes reaching up to 15 cm in length. The spikelets, bearing 6–8 flowers each, display a pale to darker reddish-brown coloration and are tightly imbricate. The fruit is an oblong-ellipsoid, trigonous achene, measuring 1.4–1.7 mm in length and 0.5–0.7 mm in width. It produces a single seed with a thin coat, distinct from the pericarp, with an embryo at the base surrounded by abundant endosperm. It occurs in diverse habitats ranging from ridges and ‘a’a lava landscapes to gulches and forests of varying moisture levels, extending into subalpine zones. Its elevation range spans from (60–)250-1980 meters.