Distribution CHINA: Sichuan, Yunnan, Xizang; INDIA: Arunachal Pradesh, Assam, Manipur, Sikkim; MYANMAR ; NEPAL; VIETNAM. Habitat Broadleaved and mixed forest, often in association with bamboos, between 2000 and 3500 m asl. USDA Hardiness Zone 7. Conservation status Data Deficient (IUCN); but included on CITES Appendix 2. Illustration NT838, NT843. Cross-references B570, K294.
Var. wallichiana occurs from central Nepal to western China as a geographically disjunct metapopulation. Outliers fitting the morphological template of var. wallichiana grow with var. mairei in southern and eastern China and southern Vietnam, but these may reflect variation in the population of the latter. As defined by Möller et al. (2007), var. wallichiana has a mean leaf density of 10 per 2 cm, mean leaf length to width ratio 10.4 (i.e. longish leaves of medium width), and a high number of stomatal bands (mean 13.2).
The definable distribution of var. wallichiana makes it possible for some collections, at least, to be confidently ascribed here. Schilling 2056, for example, grown in several British arboreta, came from mixed forest in the Dudh Kosi valley of eastern Nepal in 1975 (T. Schilling, pers. comm. 2004), east of the distribution of T. fuana; Philippe de Spoelberch’s collection from the Dochu La, Bhutan in 1985 fits here as well. Gatherings from southwestern Sichuan and western Yunnan can also be reliably identified as var. wallichiana.