Pseudostem subcylindrical, 2.5 m or taller, tufted. Inflorescence slightly curved and pendulous; bractsovate-lanceolate, 7-8 cm wide, strongly concave, dark purplish red; flowers 8 per bract, arranged in 2 series, sessile; Male flowers: periath cylindrical, 3-3.3 cm long, 5-lobed (3 lobes in outer row, 2 lobes in inner row); lobes of outer row: lateral ones oblong-triangular, 5-5.5 mm long, ca. 4 mm wide, obtuse, entire; central one ovate, 3.5 mm long and wide, obtuse; lobes of inner row obliquely ovate, ca. 4-4.5 mm long, 3 mm wide, obtuse, base cordate or auricule; posterior lobe of inner row always free, elliptic-obovate, 1.5-2 cm long, ca 1 cm wide, truncate or emerginate, and shortly cuspidate at apex; stamens 5, equalling perianth or shorter; filaments green, filiform, ca 1 cm long; anthers linear, connective slightly elongate, style column filiform, equalling stamens apex, clavate. Female flowers unknown. Rachis terete, 3 cm in diam., densely pubescent. Immature fruits obliquely tetragonal, stipitate; fruiting stalk densely pubescent.
Listed as Critically Endangered on the IUCN Red List Criteria. Population size estimated to number fewer than 20 mature individuals in 6 sites, and Decreasing. Endemic to Lanyu Island. Previously noted in two locations: Taiwan. Lanyu Island. Near the Jong-Ai Bridge, N22-00-21,E121-34-27, alt. 50-100; and Tian-Chi, N22-01-15, E121-34-21. alt., 200m. However, on my recent visit to the island I noted the species to be absent from the Jong-Ai Bridge area, and that all banana species around that location to be from cultivated decent. I confirm only one population located in 6 sites within 50 square metres on Tian-Chi alt., 290m. Grows only under the canopy at a point where sufficient light penetrates the forest canopy. Conditions seem to suggest that this species prefers cool elevation in a moist, seasonally flooded, deep, rich volcanic soil, and that it is intolerant of the dark, shadiest canopy, preferring location where sufficient sunlight meets its requirements. Lanyu’s forests were deforested 20 years ago. Nowadays, Lanyu’s forests are recovering, and I fear this dense forest cover may overwhelm the species. Annual Mean Temperature on the island is 23.9 °C. Min Temperature of Coldest Month 16.6 °C. However, the temperature at 290 m elevation is a considerably cooler climate. Annual Precipitation 2652 mm.
Native to, Taiwan
Musa insularimontana is reduced to only 6 sites within 50m. Endemic to primary forest on the southern part of Lanyu Island, Taiwan at 290m elevation.