Lobelia gloria-montis subsp. gloria-montis is an erect flowering plant, approximately 1.5 to 5 meters tall. Its stems measure between 0.4 and 4 meters tall and 1.5 to 10 cm in diameter. The stem surface is marked by distinct, transversely rhombic cicatrices 3–5 mm tall and 6–13 mm wide, with sharply acute corners. The leaves are simple and alternate, with oblanceolate to narrowly oblong blades measuring 10–24 cm long and 1.3–3.8 cm wide. Leaf apices are acute or acuminate, and the base ranges from attenuate and cuneate to obtuse. The blade surfaces are glabrous, though the margins may be ciliate near the base. Margins are thickened and may appear subrevolute. Stipules are absent. It produces a large and often unbranched to few-branched inflorescence that can reach 1 to 1.5 meters in height. Each of the 5 to 7 inflorescence branches is pyramidal and bears 18 to 100 flowers. The axis of the inflorescence is green and either glabrous or sparsely pubescent. The peduncle bears sterile bracts that decrease in size acropetally and range from 30–120 mm long and 10–25 mm wide. Floral bracts are 20–90 mm long and 6–16 mm wide. Pedicels are 15–60 mm long. The hypanthium is broadly obconic or campanulate, 8–15 mm long and 6–17 mm wide. The calyx is five-lobed with 7.5–35 mm long lobes, varying from narrowly triangular to lanceolate, and entire or ciliate with acute to acuminate apices. Sepals are connate with the tube adnate to the ovary. The corolla is zygomorphic (bilaterally symmetric), white (rarely red), and glabrous, though sometimes sparsely pubescent at the lobe apices. It is dorsally cleft almost to the base and measures 67–103 mm long. The corolla tube is 26–45 mm long, slightly curved, and 7–15 mm in diameter. Dorsal lobes are 35–70 mm long, while the ventral lip is broader, 30–52 mm long and 12–28 mm wide. The five stamens have anthers with apical tufts of white hairs and are dithecal, opening by longitudinal slits. Anthers are coherent or connate into a tube, and filaments are glabrous, 58–82 mm long. The anther tube is 4–6.5 mm in diameter, with dorsal anthers 11–16 mm long and ventral anthers 8–13 mm. The ovary is inferior and two-celled, often topped by an annular nectary disk. Placentation is axile, or parietal, when the ovary is single-celled. The style pushes through the anther tube, initially keeping the two stigmas appressed and nonreceptive, which only becomes receptive after pollen presentation. The fruits are loculicidal capsules, 27–37 mm long and 10–18 mm wide, that dehisce at the apex by two valves. Seeds are numerous, 1.5-2.5 mm long and 1–1.2 mm wide, chestnut- to honey-brown, and contain a short, straight dicotyledonous embryo embedded in oily endosperm. It is found in montane wet forests and wet mixed communities, often in bogs or along bog margins between 1,350 to 1,750 meters.