Cyrtandra subumbellata is a shrub typically growing 2–3 meters tall, with stems that are rounded to angular and range from unbranched to few-branched, pubescent with multicellular hairs or occasionally glabrate. The widely spaced, simple, opposite leaves are unequal in size, ranging from suborbicular to ovate, measuring 12–39 cm in length and 3–19 cm in width. These leaves have an acuminate apex and an abruptly constricted, decurrent base. The upper surfaces are glabrous and notably rugose, while the lower surfaces feature conspicuously raised, reticulate veins and are moderately covered with white, hemispherical, subsessile glands, occasionally with short villi along the principal veins. Leaf margins are coarsely crenate to serrate. Petioles measure 2–7 cm in length and may clasp or encircle the stem; stipules are absent. The flowers are bisexual (perfect), arranged in dense, umbelliform cymes of 5–15 flowers arising from the leaf axils at nodes below the leaves. Inflorescence parts are moderately glandular throughout, with peduncles 2–8 mm and slender pedicels 7–25 mm long. Calyx lobes are linear, green, glandular externally, and measure 12–22 mm long. The subcylindrical, white corolla tube, slightly curved and sparsely glandular, measures 18–20 mm long and expands to 8–9 mm in diameter medially, terminating in reflexed lower lobes and suborbicular upper lobes. There are two fertile stamens positioned within the corolla throat. The superior glandular ovary is oblong-ovoid with numerous ovules and a gland-covered style 10–11 mm long, topped by a capitate stigma. The fruits are white, gland-covered, fleshy berries measuring 1–1.5 cm long, each containing numerous minute, reticulate seeds. It is found in moist, shaded gulch bottoms and along streams in disturbed mesic valleys between 460–760 meters.