2. Asplenium montanum Willd. (mountain spleenwort)
Pl. 1e,f; Map 2
Leaves 3–20 cm long, monomorphic. Petioles dark brown to purplish black in the
lower 1/3–1/2, green above, not shiny. Leaf blades 2–3 times pinnately
compound, lanceolate to deltoid in outline. Pinnae alternate on the rachis,
6–35 mm long, triangular to lanceolate, the pinnules linear to oblong or ovate
and often deeply lobed, at least toward the base of the leaf blade, the pinna
bases not overlapping the rachis. Veins not anastomosing. Spores 64 per
sporangium. 2n=72. June–September.
Known only from a single collection from Montgomery
County (eastern U.S., most commonly in the Appalachians).
Ledges and crevices of shaded to somewhat exposed sandstone bluffs.
population has not been relocated and the species is now perhaps extirpated
there. The Missouri station is at the species’
western distributional limit and is disjunct, with the closest populations in
This diploid species hybridized with A. platyneuron to form the
tetraploid A. bradleyi and with A. rhizophyllum to form the
tetraploid A. pinnatifidum. Sterile, triploid backcrosses with A.
bradleyi (A. ¥wherryi D.M Sm. et al.) and A. pinnatifidum (A. ¥trudellii Wherry) have not been
reported from Missouri
and are unlikely in view of the mountain spleenwort's rarity in the state.