Asplenium adiantum-nigrum
Asplenium adulterinum
black spleenwort
adulterated spleenwort, corrupt spleenwort, ladder spleenwort
not proliferous.
not proliferous.
ascending or short-creeping, infrequently branched;
scales dark brown to blackish throughout, narrowly deltate, 2–4(–5) × 0.2–0.5 mm, margins entire or shallowly denticulate to serrulate.
short-creeping, mainly unbranched;
scales black or with narrow pale borders, narrowly lanceolate, 1.5–3 × 0.2–0.4 mm, margins entire.
monomorphic.
monomorphic.
dark reddish brown proximally, often fading to green distally, lustrous, 2–20 cm, 2/3–2 times length of blade;
indument of black filiform scales and minute hairs.
dark reddish brown throughout, 1–4 mm;
indument of black linear scales at base.
deltate, 2–3-pinnate, 2.5–10 × 2–6.5 cm, thick, hairs dark, scattered, minute;
base truncate;
apex acute to acuminate, not rooting.
linear, 1-pinnate, 2.5–14 × 0.5–1.2 cm, thick (open habitat) to herbaceous (shaded, moist habitat), essentially glabrous;
base somewhat tapered;
apex obtuse, not rooting.
in 4–10 pairs, deltate to lanceolate;
most proximal (largest) pinnae 1.5–4 × 1–2.5 cm;
base obliquely obtuse;
segment margins coarsely incised;
apex acute.
in 10–30 pairs, ovate to rhombic to ovate-oblong, 2.5–11 × 2–6 mm;
base truncate to shortly acute;
margins shallowly crenate (shade forms) to essentially entire (exposed forms);
apex obtuse, broadly rounded.
free, evident.
free, evident to obscure.
1–numerous pairs per pinna [1–6 pairs per segment], on both basiscopic and acroscopic sides.
1–3 pairs per pinna on both basiscopic and acroscopic sides.
64 per sporangium.
64 per sporangium.
greenish throughout or sometimes reddish brown proximally, lustrous, sparsely pubescent.
reddish brown in proximal 1/2–4/5, green distally, lustrous, glabrous.
= 144.
= 144.
Asplenium adiantum-nigrum
Asplenium adulterinum
Asplenium adiantum-nigrum is principally a Eurasian species and occurs extremely rarely in North America (see M. G. Shivas 1969 and M. D. Windham 1983 for a discussion of the conspecificity of Western Hemisphere and Eastern Hemisphere material). It is an allotetraploid derived from hybridization of two European taxa, A. cuneifolium Viviani and A. onopteris Linnaeus (M. G. Shivas 1969). Hybrids involving A. adiantum-nigrum and other Asplenium species occur in Europe but are unknown in North America.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
In North America Asplenium adulterinum is known to occur on Vancouver Island, British Columbia, where only the fertile allotetraploids are known. It is likely to occur in areas where the two parents, A. trichomanes and A. trichomanes-ramosum, grow together. The genetics of the American plants should be compared with that of the European, among which two nothosubspecies occur (F. Mokry et al. 1986).
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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