Pinus roxburghii, commonly known as chir pine or longleaf Indian pine, is a species of pine tree native to the Himalayas. It was named after William Roxburgh. Description Pinus roxburghii is a large tree reaching with a trunk diameter of up to , exceptionally . The bark is red-brown, thick and deeply fissured at the base of the trunk, thinner and flaky in the upper crown. The leaves are needle-like, in fascicles of three, very slender, long, and distinctly yellowish green. The cones are ovoid conic, long and broad at the base when closed, green at first, ripening glossy chestnut-brown when 24 months old. They open slowly over the next year or so, or after being heated by a forest fire, to release the seeds, opening to broad. The seeds are long, with a wing, and are wind-dispersed. Similar species Pinus roxburghii is closely related to P. canariensis (Canary Island pine), P. brutia (Turkish pine) and P. pinaster (maritime pine), which all share many features with it. It is a relatively non-variable species, with constant morphology over the entire range. Chemistry Pinus roxburghii contains large amounts of taxifolin. Distribution and habitat The native range extends from Tibet and Afghanistan through Pakistan, across northern India (in Jammu and Kashmir, Himachal Pradesh, Uttarakhand, Sikkim and Arunachal Pradesh), Nepal and Bhutan, to Myanmar. It generally occurs at lower altitudes than other pines in the Himalayas, from , occasionally up to . The other Himalayan pines are P. wallichiana (blue pine), P. bhutanica (Bhutan white pine), P. armandii (Chinese white pine), P. gerardiana (chilgoza pine), P. densata (Sikang pine) and P. kesiya (Khasi pine). Ecology Owing to its shallow roots it is attributed to soil erosion, particularly in the Himalayas. It does not allow any vegetation to grow around it by making soil more acidic through its fallen needles. Usually, the accumulating carpet of needles on the forest floor under these trees makes conditions unfavourable for many common plants and trees to grow. The most common trees which are able to grow in this environment are Rhododendron, banj oak (Quercus leucotrichophora) and trees from the family Ericaceae (known locally as eonr and lodar). This could possibly be due to the relative immunity from fire that the thick bark of these species gives them. The Himalayan nettle (Girardinia diversifolia) is another plant which seems to thrive well under this tree. The caterpillars of the moth