Adiantum tricholepis
Adiantum tricholepis Fee
(Greek: thrix, trichos, hair, and lepis, scale, = hairy scale)
Local names: hairy maidenhair fern, fuzzy maidenhair fern
Rhizomes short-creeping to ascending or suberect; leaves clumped, lax-arching, to 70 cm tall; leaf blades 3–4-pinnate, minutely hairy on both upper and lower surfaces with numerous stiff whitish hairs to 0.5 mm long, the ultimate segments fan-shaped to transversely oblong to nearly round; petioles and rachis dark reddish brown, somewhat stouter than in A. capillus-veneris. Limestone cliffs along streams, on boulders in creeks, and among rocks on steep slopes; Medina (e.g., J. Stanford 5002, BRIT, HPC; Correll 14112, BRIT, TEX-LL; G.M. Soxman 89, TEX-LL) and Bandera (Correll 1956; Paris 1993; no recent collections known in Bandera) cos. on the Edwards Plateau; in the U.S. known only from these 2 counties in TX; also Mexico, Belize, and Guatemala. Sporulating spring through Nov, depending on rains. Correll (1956, 1966) and Paris (1993) noted that specimens from the mouth of the Pecos River are actually A. capillus-veneris. Seigler and Lockwood (1975) emphasized that the Edwards Plateau is “well known for its unusual ferns” pointing out that a number of tropical ferns, Adiantum tricholepis, Dennstaedtia globulifera, Blechnum appendiculatum (as B. occidentale var. minor), and Tectaria heracleifolia, have been found in the area, “which is the extreme northern limit of their ranges.” This is one of 19 pteridophyte species known in the U.S. only from TX (see page 41). Because of its rareness and limited distribution in the state, we consider it to be of conservation concern in TX (and in the U.S.).