Cyanea hamatiflora subsp. carlsonii is a palm-like tree that reaches 3–8 meters and has tan latex. The leaves are simple and alternate, with blades that are oblanceolate to narrowly oblong, measuring 50–80 cm in length and 8–14 cm in width. The apex is acute. The upper surfaces of the leaves are glabrous or sparsely pubescent, while the lower surfaces are pubescent, at least along the midrib and veins. The margins are minutely callose-denticulate. The leaves are sessile, and stipules are absent. The inflorescences comprise 5–10 flowers, axillary in position. The peduncles are 15–30 mm long, and the pedicels are 8–12 mm long. The hypanthium is obconical to obovoid, measuring 12–30 mm long and 6–12 mm wide. The flowers are bisexual (perfect). The calyx has five narrowly oblong lobes, 30–45 mm long and 5–6 mm wide, with an obtuse and apiculate apex. The tube is adnate to the ovary. The corolla is zygomatic and magenta, 60–80 mm long and 6–11 mm wide, glabrous. The tube is suberect to slightly curved, and the lobes are connate, ¼–1⁄2 as long as the tube, all curved downward in the same plane, giving the corolla a unilabiate appearance. There are five stamens, alternate with the corolla lobes and connate. The staminal column is glabrous or pubescent at the base. The anthers are glabrous, with the lower 2 having apical tufts of white hairs, dithecal, and opening by longitudinal slits. The anthers are coherent but separate after anthesis or are connate. The filaments are distinct or connate above, attached to the epigynous nectary disk or to the base of the corolla, and rarely adnate to the corolla tube. The ovary is inferior and 2-celled, with ovule placentation axile. The stigma is 2-lobed, wet or dry, appressed, and nonreceptive as the style grows through the anther tube, pushing out the pollen, after which the stigmas spread apart and become receptive. The fruit is a purplish-red berry, ellipsoid to obovoid, measuring 30–45 mm long and 20–27 mm wide, and crowned by the persistent calyx lobes. The seeds are numerous, small, brown to black, smooth, shiny, and measure approximately 1.5 mm long, with a straight, short to spatulate dicotyledonous embryo embedded in oily endosperm. It occurs in wet forests at 1,300–1,740 meters.