Wikipedia:Today's featured article/November 27, 2013

Adiantum viridimontanum, commonly known as Green Mountain maidenhair fern, is a rare fern found only in outcrops of serpentine rock in New England and Canada. It is named after the site of its discovery in the Green Mountains in Vermont; it has since been located in Quebec and in one site on serpentine in coastal Maine. 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. It was then established that A. viridimontanum was a hybrid species and that the other two ferns were distinct species, although it is difficult to distinguish between the three species 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 road cuts, talus slopes, and asbestos mines. Individual plants seem long-lived, and new individuals only infrequently reach maturity. It is one of four species endemic to serpentine in eastern North America and is considered globally threatened due to its habitat restrictions.

Recently featured: 13th Airborne Division (United States) – History of the National Hockey League (1942–1967) – Goblin shark