Asplenium pinnatifidum
Asplenium ruta-muraria
lobed spleenwort
doradille des murailles, wall rue, wall-rue spleenwort
not proliferous.
not proliferous.
short-creeping to erect, frequently branched;
scales dark reddish brown, narrowly deltate, 3–5 × 0.3–0.5 mm, margins entire.
short-creeping to erect, often branched;
scales very dark brown throughout, narrowly deltate, 1–3 × 0.1–0.25 mm, margins with widely spaced teeth.
monomorphic.
monomorphic.
dark reddish brown at base, fading to green in distal 1/3–1/2, lustrous, 1–10 cm, 1/5–1 times length of blade;
indument of dark reddish brown, narrowly deltate scales at very base, grading distally into hairs.
reddish brown proximally, green distally, dull, 1–9 cm, (1/2–)1–2 times length of blade;
indument of dark brown, narrowly deltate scales proximally grading into multicellular hairs.
narrowly deltate, often irregular in outline, pinnatifid or often with single pair of pinnae proximally, 2–17(–20) × 1–4(–13) cm, thick, pubescent abaxially only;
base truncate, cordate, or auriculate;
apex acute to long-attenuate, proliferous bud very rare, not known to root in nature.
deltate-ovate to obovate or oblanceolate, 1–2(–3)-pinnate to 2-pinnate-pinnatifid, 2–6 × 1–4 cm, somewhat thick, glabrous;
base obtuse;
apex acute to rounded, not rooting.
0–1 pair, ovate to deltate, sometimes narrowly so, 5–20(–90) × 0.4–1(–1.2) mm;
base truncate to acute;
margins crenate to serrate;
apex rounded to attenuate.
in 2–4 pairs, deltate-ovate to obdeltate;
proximal (largest) pinnae 7–30 × 5–20 mm;
base truncate to acute;
margins finely (sometimes coarsely) incised;
apex rounded to acute.
free (rarely anastomosing), obscure.
free, evident.
1–6(–40+) per segment, usually confluent with age.
as many as 30 or more per pinna, usually 1–5 per segment, on both basiscopic and acroscopic sides.
64 per sporangium.
64 per sporangium.
green, sometimes drying to tan, dull;
hairs on abaxial surface only, scattered, minute.
green, dull, glabrous except for very sparse, minute hairs.
= 144.
= 144.
Asplenium pinnatifidum
Asplenium ruta-muraria
Asplenium pinnatifidum is an allotetraploid derived from the hybrid A. montanum × rhizophyllum. Although isozyme studies indicate that this species originated at more than one site (C. R. Werth et al. 1985b), the sterile diploid hybrid is unknown. The species is uncommon in the eastern part of the Appalachian region and becomes much more frequent in the Cumberland and Interior Low plateaus, extending westward into the Ozarks and Ouachitas. It is disjunct in the Driftless Area of Wisconsin in Iowa County (M. G. and R. P. Hanson 1979). It crosses frequently with A. montanum (producing A. × trudellii Wherry), with A. bradleyi (producing A. × gravesii Maxon), with A. platyneuron (producing A. × kentuckiense McCoy), and with A. trichomanes (producing A. × herb-wagneri W. C. Taylor & Mohlenbrock).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
The relationship of North American Asplenium ruta-muraria to its European counterparts is incompletely understood and bears further investigation. Based on features of the stems, M. L. Fernald (1928) segregated the North American taxon as A. cryptolepis, but most current authors agree that morphologic differentiation of North American and European material is too slight and inconsistent for recognition at the specific level. In Europe, two ploidy levels are treated as subspecies, diploid A. ruta-muraria subsp. dolomiticum Lovis & Reichstein and tetraploid A. ruta-muraria subsp. ruta-muraria, the latter representing the most compelling case for true autopolyploidy (i.e., based on chromosomal homology) known in ferns (G. Vida 1970). Chromosome counts of North American plants are consistently tetraploid; whether or not these plants are referable to subsp. ruta-muraria will remain unclear until additional evidence (e.g., isozymes) is obtained. Meanwhile, North American material should be designated simply as A. ruta-muraria, the convention used in most current manuals.
Although M. L. Fernald (1928) recognized Asplenium cryptolepis var. ohionis (= A. ruta-muraria var. subtenuifolium Christ), based on its acute rather than rounded segment apices, leaves assignable to this variety may occur on plants also bearing leaves more similar to those of the type variety (R. Cranfill 1980). The former is not recognized taxonomically here.
Numerous hybrids of Asplenium ruta-muraria with various taxa are known from Europe (T. Reichstein 1981), but only three are known from North America, all exceedingly rare. These are the hybrids with A. rhizophyllum (A. × inexpectatum), with A. trichomanes (A. × clermontae Syme), and with A. platyneuron (A. × morganii).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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