Wikipedia:Today's featured article/October 13, 2022

Adiantum viridimontanum, the Green Mountain maidenhair fern, is a rare fern found in outcrops of serpentine rock in New England and Quebec. It is named after the site of its discovery in the Green Mountains in Vermont. Until 1991, it was grouped with the western maidenhair fern A. aleuticum, which itself was classified as a variety of the northern maidenhair fern A. pedatum. A. viridimontanum is a hybrid species and the other two ferns are distinct species, although it is difficult to distinguish between the three in the field. Due to the limited distribution of A. viridimontanum and its similarity to other species, little is known of its ecology. It thrives on sunny, disturbed areas where ultramafic rock is covered with thin soil, such as roadcuts, talus slopes, and asbestos mines. Individual plants seem long-lived, and new ones only infrequently reach maturity. One of four species endemic to serpentine in eastern North America, it is considered vulnerable due to its habitat restrictions.