Geographically, the province is surrounded by the foothills of the Himalayas and plain regions of the Nepal border in the north, constituting a major part of the Terai region, which is conducive to the establishment of pteridophytes. The state is bordered by Uttarakhand, Haryana, Delhi, and the xeric areas of Rajasthan in the northwest, west, and southwest region; by Madhya Pradesh, Chhattisgarh, and Jharkhand in the south and south-east; and Gangetic plains of Bihar in the east. Both the northeast and the southwest monsoons, with an average rainfall of 99-201 cm, have a significant role in the establishment of pteridophytic diversity (Singh et al. 2017). The unique biogeography, ecological conditions, and microclimatic niche of the province contribute to a substantial richness of the fern allies and ferns as they prefer to grow in shady, cool, and humid climates.
