Cyanea tritomantha is a palm-like tree reaching heights of 1.8–3 meters. Its leaves are simple and alternate, with oblong to oblanceolate or obovate blades measuring 38–95 cm in length and 11–20 cm in width. The leaf apex ranges from acuminate to acute or obtuse, with a cuneate to attenuate base. The upper surfaces are green and glabrous, while the lower surfaces are pale green, pubescent, and muricate along the midrib. The margins are callose-denticulate, and the petioles, 2–18 cm long, are muricate. The inflorescences comprise 5–20 flowers clustered among the leaves, with peduncles 20–75 mm long and pedicels 12–30 mm long. The hypanthium is obconical, measuring 10–14 mm long and 5–8 mm wide. The calyx is 5-lobed with narrowly triangular lobes 10–25 mm long and 1.5–3 mm wide, acuminate and apiculate at the apex. The corolla is zygomorphic (bilaterally symmetric), blackish purple or greenish white externally, pale bluish-white or white within, 60–75 mm long and 5–6 mm wide, densely pubescent, and the tube is suberect to slightly curved. Stamens are connate, with a glabrous staminal column and anthers with apical tufts of white hair on the lower two. The ovary is inferior and 2-celled, with axile ovule placentation. The fruit is an orange ellipsoid berry, 15–25 mm long and 10–22 mm in diameter, crowned by the persistent calyx lobes. It contains numerous small, brown to smooth black seeds, shiny, ca. 0.6-0.7 mm long, and has a straight, short to spatulate dicotyledonous embryo embedded in oily endosperm. It is found in wet forests at elevations of 350–1,080 meters.