Geniostoma triflorum is a scandent shrub or small tree, 2–6 meters tall. The stems are dichotomously branched, and young branches are terete (cylindrical) and glabrous. The leaves are simple and opposite, with lanceolate blades to elliptic-lanceolate, measuring 7–14 cm long and 2–4 cm wide, membranous. The apex is acuminate, and the base is cordate, ± asymmetrical. The surfaces are dark green; veins are not impressed on the upper surface and are glabrous. The margins are flat, entire, or rarely toothed. The petioles are 1–3 mm long. The stipules are completely connate, forming a truncate sheath 1–4 mm long, sometimes splitting with age, slightly adnate to the base of the petioles, with entire, sometimes ciliolate margins. The flowers are in terminal inflorescences, with 3–14 flowers (female flowers, 3–5 [–7]; male flowers, 3–14) in pendulous, open, paniculate cymes, and glabrous throughout. The peduncles are weakly recurved, 40–50 mm long, elongating to 70–80 mm long in fruit. The pedicels are 10–25 mm long, elongating up to 30 mm in fruit. The bracts and bracteoles are subulate, 1–2 mm long. The flowers are unisexual and actinomorphic (radially symmetric). The calyx is 5-merous, with calyx lobes connate to about 1/2 their length, imbricate, ovate-deltate, 1–4 mm long, and 1–2.5 mm wide. The inner surface of the calyx often has colleters at the base, and the margins are hyaline and ± ciliolate. The corolla is 5-merous, pale or greenish-yellow, urceolate, 7–12 mm long, with a tube 6–10 mm long, 1.5–2 mm in diameter (~slightly enlarged at the base, 3.5–4 mm in diameter). The outer surface is glabrous to short-hairy, sparsely pilose within, and the lobes are deltate-ovate, 1.5–2.5 mm long, imbricate or contorted in the bud, with a short acuminate to rounded apex. The stamens are 5, alternipetalous, attached to the mouth of the corolla, exserted, usually recurved after anthesis, glabrous or hairy. The filaments are primarily short, and the anthers are 2-celled, introrse, with the connective often extended to form an apical appendage, opening by longitudinal slits. The fruit is a capsule broadly ovoid to subglobose-ovoid or ellipsoid-ovoid, measuring 9–20 mm long, two-valved, with transversely wrinkled valves and not keeled. The apex has a beak 1–2 mm long, and the fruit is septicidal to sub-septifragal, maturing to green, with or without a black-purple tinge, usually becoming brown-black when over-mature. The seeds are ± winged at both ends or all around, embedded in juicy orange to red pulp, numerous, ellipsoid to subglobular, intruded on the hilar side, brown, 2–2.5 mm long. The endosperm is thick, fleshy, oily, proteinaceous, with saccharose or hemicellulose, and the embryo is small and straight. It is found in mesic forests on west-facing slopes of ravines, with well-drained, loose, rocky substrate at approximately 800 meters.