Clermontia micrantha is a terrestrial shrub ranging in height from 0.4 to 2 meters. The stems are repeatedly branched and spreading, with a light gray or light brown coloration. They are typically glabrous, rarely pubescent, and display numerous helically arranged leaf scars near the apex. The pith is solid and contains a white, viscous latex. The leaves are simple and alternate, with elliptic or oblong blades measuring 4 to 10 cm in length and 1 to 2.5 cm in width. The apex is acute or acuminate, and the base is cuneate or attenuate. The leaf surfaces are glabrous and coriaceous, appearing dull in texture. Upper surfaces are green to dark green, while lower surfaces are light green and often suffused with magenta, especially along the veins. The margins are callose-crenulate. Petioles range from 1.5 to 4 cm long and are glabrous. Stipules are absent. The inflorescences bear 2 to 5 glabrous flowers. Each has a peduncle 0.5 to 1 cm long, which is spreading and bibracteate at the apex. The pedicels are 0.7 to 1.4 cm long, spreading, and bibracteolate near the base. Flowers are bisexual, epigynous, zygomorphic (bilaterally symmetric), resupinate, and protandrous. The hypanthium is obovoid or turbinate, glabrous, and measures 5 to 8 mm in length and 3 to 7 mm in diameter. The perianth is 1.8 to 2.8 cm long, rotate, rose-colored, and glabrous. Its tube is 0.7 to 1.3 cm long and 3 to 5 mm in diameter, suberect, while the lobes are 1 to 1.6 cm long and 1 to 2.7 mm wide and recurved. There are five stamens, syngenesious, alternating with the corolla lobes. The staminal column is exserted and erect or suberect. Anthers are connate, dithecal, and open introrsely via longitudinal slits. They are purple, with the three dorsal anthers slightly longer than the two ventral ones, which often bear tufts of stiff white trichomes at the apex. Otherwise, the anthers are glabrous, though sometimes pubescent along the sutures or on the surface. The anther tube is 6 to 8 mm long and 1.8 to 2.2 mm in diameter and may be glabrous or pubescent. Filaments are connate above, free from the corolla, 1.7 to 2 cm long, rose or purple, and glabrous. Pollen grains are tricolporate, prolate, and ellipsoidal. The ovary is inferior, 2-carpellate, and 2-loculed, with axile placentation and large placentae. The style is slender and cylindrical, with a ring of stiff white hairs near the apex. The stigma is 2-lobed, with the lobes initially appressed and non-receptive as the style elongates through the anther tube to release pollen. Once this process is complete, the stigma lobes spread apart and become receptive. The fruit is a berry that is orange in color, obovoid or subglobose in shape, and measures 1.2 to 1.5 cm in length and 0.9 to 1.5 cm in width. The seeds are numerous, tiny, dark brown or black, shiny, and minutely foveate-reticulate. They contain a straight, short to spatulate dicotyledonous embryo embedded in oily endosperm. It is found in montane bogs and rainforests between 670-1,460 meters.