Hylodesmum repandum is a perennial herb or slender shrub with a woody base, climbing, scrambling, or forming dense undergrowth, 0.5–1.0 m tall. The stem is brown to reddish, from simple to greatly branched, terete to angular, hairy when juvenile, usually moderately to sparsely spreading pilose (covered with soft, slender hairs), smooth at the adult stage.

The leaves are dark green, trifoliolate (have 3 leaflets), with stipules 10–26 mm long, oblong-lanceolate to attenuate, about 2–6 mm wide, hairy on the upper surface and paler on the lower surface. The petiole is linear, covered with very fine hairs and usually long and flat; 8–110 mm long with a 5–20 mm long rachis. The leaflets are diamond-like in outline, with a sharply pointed apex and cuneate (wedge-shaped) leaf base; margin entire to repand (wavy); the upper surface is moderately long-strigose (covered with stiff hairs), whereas the lower surface, especially the veins, are more abundantly covered with small hairs; the margins usually ciliate (with a fringe of hairs). The terminal leaflets are 18–110 mm long and 15–85 mm wide.

Inflorescences elongate, 70–30 mm long, loose, terminal or axillary, racemose or racemose-paniculate, with a rachis that is uncinulate-puberulent (covered with minute hooked hairs) to moderately to densely soft spreading pilose. Bracts are 3.5–7.0 mm long and 2–3 mm wide, not long persistent, primary ovate-attenuate, puberulent (covered with minute hairs) with multicellular hairs and somewhat pilose on the outer surface, each subtending a fascicle (bundle) of 2–5 pedicels. The secondary bracts are 0.5–2 mm long and 0.3–0.5 mm wide, very small and ciliate (have a fringe of hairs on the margin), whereas the pedicels are 12–35 mm long, slender and lax, with pubescence similar to that of the rachis. Flowers are conspicuous, ranging from bright orange to brick-red. The calyx is 5.5 mm long, puberulent throughout and somewhat pilose on the teeth of both lobes. Corolla usually at least twice the length of the calyx, 8.0–12.5 mm long and 7.0–10.5 mm wide; standard almost orbicular, shortly clawed, with the wings being nearly oblong, long-auricled, shortly clawed, slightly shorter than standard, and the keel-petals are randomly elliptic, obtuse at apex, clawed, exceeding the other petals in length, being more than 14 mm long and 3.5 mm wide. Fruits are stipitate (on a small stalk), with the stipe being 2.0–4.5 mm long.

Pods are 13–45 mm long, flat, sticky, bluish green and dark chestnut-brown when ripe and separating into 1-seeded, crescent-shaped portions. It flowers from midsummer to midwinter (from December to June).