Asplenium montanum
Asplenium platyneuron
mountain spleenwort
brownstem spleenwort, doradille ébène, ebony spleenwort
proliferous.
not proliferous.
horizontal, often arching upward, unbranched (although clusters of stems often form from root proliferations, giving false appearance of single much-branched stem);
scales dark brown throughout, narrowly deltate, 2–4 × 0.2–0.4 mm, margins entire.
short-creeping, unbranched;
scales dark brown to black throughout, narrowly linear-deltate, 2–4 × 0.3–0.6 mm, margins entire.
monomorphic.
± dimorphic;
fertile leaves taller and more erect than sterile leaves.
dark brown to purplish black, lustrous proximally, fading to green distally, 2–11 cm, 1/2–1 1/2 length of blade;
indument of blackish, narrowly lanceolate scales only at very base and of minute hairs.
reddish brown throughout, lustrous, 1–10 cm, 1/4–1/3 length of blade;
indument of dark brown to black, filiform scales at base.
deltate to lanceolate, 1–2-pinnate-pinnatifid, 2–11 × 1–7(–10) cm, thick, essentially glabrous;
base truncate or obtuse;
apex acuminate to acute, not rooting.
lustrous, linear to narrowly oblanceolate, 1-pinnate throughout, 4–50 × 2–5(–7) cm, thin, glabrous, or occasionally sparsely pubescent;
base gradually tapered;
apex acute, not rooting.
in 4–10 pairs, deltate to lanceolate;
proximal (longest) pinnae 6–35 × 4–20 mm;
base obtuse to acute;
margins coarsely incised;
apex acute to rounded.
in 15–45 pairs, oblong to quadrangular;
medial pinnae 1–2.5 × 0.3–0.5 cm;
base with conspicuous acroscopic and sometimes basiscopic auricle, this overlapping rachis;
margins crenate to serrulate, sometimes more deeply incised in robust specimens;
apex acute to obtuse.
free, obscure.
free, evident.
1–15 per pinna, on both basiscopic and acroscopic sides.
1–12 pairs per pinna, on both basiscopic and acroscopic sides.
64 per sporangium.
64 per sporangium.
green throughout, dull, sparsely pubescent.
reddish or purplish brown throughout, lustrous, glabrous.
= 72.
= 72.
Asplenium montanum
Asplenium platyneuron
Asplenium montanum occurs principally in the Appalachian region, with outlying localities in the Shawnee Hills of western Kentucky (R. Cranfill 1980) and adjacent Indiana (D. M. Smith 1956). A report of its disjunct occurrence on the northern edge of the Ozarks is based on a single specimen whose label indicates the collection locality near Graham Cave, Montgomery County, Missouri. Efforts by several botanists to relocate the population have failed. Reports of a disjunct station in the upper peninsula of Michigan are doubtful.
Asplenium montanum is an ecological specialist. It is typically the sole vascular plant species in the siliceous rock crevices in which it is found. It may occur, however, with two allotetraploid species, A. bradleyi and A. pinnatifidum, which were derived from hybrids of A. montanum with A. platyneuron and A. rhizophyllum, respectively. In addition, A. montanum crosses frequently with A. pinnatifidum producing A. × trudellii and rarely with allotetraploid individuals of A. bradleyi producing A. × wherryi.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
The combining author for Asplenium platyneuron is often given as Oakes ex D. C. Eaton; see D. B. Lellinger (1981) for justification of the authorship employed here.
Asplenium platyneuron is remarkable in that it occurs in southern Africa as well as in North America. No other North American fern has this distribution. Asplenium platyneuron is an ecological generalist and is particularly characteristic of disturbed woodlands. This species is migrating northward on the northern portions of its range in the upper Great Lake states (W. H. Wagner Jr. and D. M. Johnson 1981). Proliferous buds on the lowest pinnae allow formation of clumps with stems at several layers in the litter. Asplenium platyneuron hybridizes with A. rhizophyllum, A. trichomanes (producing A. × virginicum Maxon), A. pinnatifidum, A. ruta-muraria (producing A. × morganii W. H. Wagner & F. S. Wagner), A. bradleyi, and A. montanum (producing sterile A. bradleyi).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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