Asplenium montanum
Asplenium ×heteroresiliens
mountain spleenwort
Morzenti's spleenwort, 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.
erect, rarely branched;
scales black throughout, linear-lanceolate, 1–3.5 × 0.1–0.4 mm, margins entire.
monomorphic.
monomorphic.
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.
black or purplish black throughout, lustrous, 1–2 cm, 1/5–1/10 length of blade;
indument of 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.
linear to narrowly oblanceolate, 1-pinnate throughout, 5–15 × 1–2 cm, thick, glabrous;
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 12–30 pairs, oblong to quadrangular;
medial pinnae 5–10 × 2–3 mm;
base with slight or prominent acroscopic auricle and often with basiscopic auricle;
margins usually shallowly crenulate, rarely ± entire;
apex acute to obtuse.
free, obscure.
free, obscure.
1–15 per pinna, on both basiscopic and acroscopic sides.
1–5 pairs per pinna, on both basiscopic and acroscopic sides.
64 per sporangium.
32 per sporangium.
green throughout, dull, sparsely pubescent.
black or purplish black throughout, lustrous, glabrous or with a few scattered scales.
= 2n = 180 (apogamous).
= 72.
Asplenium montanum
Asplenium ×heteroresiliens
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.)
V. M. Morzenti (1966) studied the cytology and morphology of Asplenium × heteroresiliens and found it to be a pentaploid (5 x) of hybrid origin between A. resiliens (3 x) and A. heterochroum (4 x). The hybrid is intermediate in morphology between the parents, and it is difficult to separate from them. Misshapen spores mixed with large globose spores can usually be found on the same specimen.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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