Asplenium ruta-muraria
Asplenium heterochroum
doradille des murailles, wall rue, wall-rue spleenwort
bicolor spleenwort, varicolor spleenwort
not proliferous.
not proliferous.
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.
erect or ascending, rarely branched;
scales black throughout, linear-lanceolate, 2–3 × 0.2–0.4 mm, margin entire, apex attenuate.
monomorphic.
monomorphic.
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.
black or purplish black throughout, lustrous, 0.3–5 cm, 1/4–1/15 length of blade;
indument of black filiform scales at base.
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.
linear or narrowly oblanceolate, 1-pinnate throughout, 6–22(–37) × 1–1.8(–2.3) cm, thin, glabrous;
base tapered;
apex acute, not rooting.
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.
in 15–40 pairs, oblong;
medial pinnae somewhat asymmetric, oblong, 4–10 × 2–4(–5) mm;
base acute, acroscopically enlarged;
margins serrate to crenate, lobed;
apex obtuse.
free, evident.
free, evident.
as many as 30 or more per pinna, usually 1–5 per segment, on both basiscopic and acroscopic sides.
3–6 pairs per pinna, on both basiscopic and acroscopic sides of pinnae.
64 per sporangium.
64 per sporangium.
green, dull, glabrous except for very sparse, minute hairs.
black throughout, lustrous, glabrous.
= 144.
= 144, 216.
Asplenium ruta-muraria
Asplenium heterochroum
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.)
The tetraploid cytotype (4 x) of Asplenium heterochroum hybridizes with A. resiliens (3 x) to produce A. × heteroresiliens (5 x). It is extremely rare and local, known in northern peninsular Florida from Alachua, Citrus, Columbia, Jackson, and Marion counties.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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