Sikkim is a land-locked state in the North-east of India. It is located in the ecological hotspot of lower Himalayas. Sikkim exhibits a diverse range of flora and fauna. Owing to its attitudinal gradation, the state has a wide variety of plants, from tropical to temperate to alpine and tundra, and is perhaps one of the few regions to exhibit such a diversity within such a small area. Nearly 81% of the area of Sikkim comes under the administration of its forest department. The flora of Sikkim include the rhododendron, the state tree, with a wide range of species occurring from subtropical to alpine regions.
Sikkim has around 5,000 flowering plants, 515 rare orchids, 60 primula species, 36 rhododendron species, 11 oak varieties, 23 bamboo varieties, 16 conifer species, 362 types of ferns and ferns allies, 8 tree ferns, and over 424 medicinal plants. This particular checklist lists 146 species of important trees found in Sikkim.