Grierson, D.G.Long & C.N.Page
Description
Pinus bhutanica Grierson, D.G.Long & C.N.Page is a five-needled white pine of the eastern Himalaya, restricted to Bhutan, north-eastern India (Arunachal Pradesh) and adjacent south-eastern Tibet (China); GBIF records about 96 occurrences, the few extralimital points reflecting cultivation or database artefacts. It grows in warm-temperate to subtropical montane forest, often on humid, monsoon-exposed slopes, typically between about 1,700 and 2,400 m. Both photographed stands are Bhutanese – Trongsa at 2,300 m in October and Chongsakha at 1,800 m in May – matching its known occurrence in the wet central and eastern Bhutanese hills.
It is an evergreen coniferous tree to 25 m or more, with spreading branches and a somewhat open crown. The needles are borne in fascicles of five, and are notably long, slender and pendulous, drooping gracefully and distinguishing it from the related P. wallichiana. The species is monoecious, with small pollen cones clustered at the base of new shoots and erect young seed cones that mature in the second year. The mature cone is large, cylindrical and resinous, with thin woody scales; the seeds are winged for wind dispersal, borne beneath the cone scales.
Pinus bhutanica was described as recently as 1980 and belongs to subgenus Strobus (the soft or white pines), being closely allied to the widespread Himalayan blue pine P. wallichiana, from which it differs chiefly in its longer, conspicuously drooping needles and more pronounced resin glands. Its narrow eastern Himalayan range makes it of biogeographic interest as a regional endemic of the wetter Bhutan-Arunachal sector; it is assessed by IUCN as Least Concern owing to stable populations within extensive forest.
Author: Grierson, D.G.Long & C.N.Page · Sources: POWO (Kew), GBIF, Flora of Bhutan, Flora of China, IUCN Red List of Threatened Species, Farjon Handbook of the World's Conifers, Grierson Long & Page protologue of Pinus bhutanica