Adiantum viridimontanum Paris
Green Mountain Maidenhair Fern
Habitat: Serpentine steep clifs and talus slopes, and thin soils of woodlands and forest edges on serpentine bedrock. [Rocky summits and outcrops (non-forested, upland)]
Range: Limited to serpentine areas of northern Vermont, northern and Downeast Maine, and southern Quebec.
Aids to Identification: Maidenhair ferns have thin, delicate leaflets on shiny black stems, with the sori forming on veins under the reflexed lobe margins. The Green Mountain maidenhair fern can be distinguished from northern maidenhair fern (Adiantum pedatum) by having more upright leaves (vs. more horizontal), long and triangular ultimate leaf segments (vs. oblong), longer petiole length, and longer and wider indusia. Northern maidenhair fern also grows in non-serpentine habitats and prefers shaded areas with deep, enriched woodland soils. Green Mountain maidenhair fern can be distinguised from Aleutian maidenhair (Adiantum aleuticum) fern by having larger leaf size, longer indusium length, and a lesser degree of incision between leaf segments. Aleutian maidenhair fern is usually associated with less disturbed sites. Morphological and ecological distinctions can blur with plants in partial shade, and hybrids can form where species occur together, so field identification can be difficult.
Ecological characteristics: Restricted to serpentine soils.
Synonyms: None. Split from the Adiantum pedatum complex and formally described as a new species in 1991.
Known Distribution in Maine: This rare plant has been documented from a total of 2 town(s) in the following county(ies): Franklin, Hancock.
Reason(s) for rarity: Habitat naturally scarce.