The Bhutan Himalaya forms a substantial part of the Eastern Himalaya with a huge elevation gradient from the low southern foothills with sub-tropical forests to the high northern Himalayas with alipine meadows. Its high variations of climatic and geographic factors contribute to high biodiversity. Over 5600 species of vascular plants occur in Bhutan, of which 423 are orchids including 54 species of new records (Gurung 2006) and some 46 species of Rhododenron (Flora of Bhutan 1991). The family of orchids, Orchidaceae, is the largest, followed by Poaceae, the grass family. Unlike neighboring states of India and Nepal, pteridophytes of Bhutan have remained largely unstudied.

Currently, a total of 411 species of ferns in 27 familes are recognized in Bhutan. The list, however, is not exhaustive. More species are likely to be encountered, possibly new ones, if a detailed study is carried out. The list was initially based on literature review and was later authenticated through examination of herbarium specimens and field collections. This checklist treats Athyriaceae Alston, previously treated as a separate family, as subfamily Athyrioideae within family Aspleniaceae following 2014 Christenhusz and Chase. Lygodium has been placed in Schizaeaceae, not Lygodiacae as some botanists prefer.

Reference: Fraser-Jenkins, C.R., Matsumoto, S. & Wangdi, T., in Fraser-Jenkins, C.R. (ed.). 2009. Pteridophytes of Bhutan - A list of families, genera and species: i-x, 1-125. National Biodiversity Centre, Ministry of Agriculture, Serbithang, Thimphu, Bhutan.