Asplenium adiantum-nigrum
Asplenium dalhousiae
black spleenwort
Countess dalhousie's 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.
erect, unbranched;
scales black with brown margins, lanceolate, 2–5 × 0.6–1 mm, sparsely denticulate.
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 to light brown throughout, dull, to 1 cm, 1/10–1/15 length of blade, indument of scales throughout.
deltate, 2–3-pinnate, 2.5–10 × 2–6.5 cm, thick, hairs dark, scattered, minute;
base truncate;
apex acute to acuminate, not rooting.
narrowly elliptic to narrowly lanceolate, pinnatifid, 4–15 × 1.5–6 cm, thick, sparsely puberulent to glabrescent;
base gradually 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.
free, evident.
free, obscure.
1–numerous pairs per pinna [1–6 pairs per segment], on both basiscopic and acroscopic sides.
3–7 pairs per pinna, on both basiscopic and acroscopic sides of lobes.
64 per sporangium.
64 per sporangium.
greenish throughout or sometimes reddish brown proximally, lustrous, sparsely pubescent.
light brown to tan, dull-scaly;
scales brown, lanceolate.
= 144.
= 72.
Asplenium adiantum-nigrum
Asplenium dalhousiae
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 the flora, Asplenium dalhousiae is found only in the Mule, Huachuca, and Baboquivari mountains of southern Arizona. The pattern of disjunction in the worldwide range of this species is highly unusual.
Asplenium dalhousiae is sometimes placed in the genus Ceterach on the basis of its thick, pinnatifid leaves. Most pteridologists, however, restrict Ceterach to species with densely scaly, pinnatifid leaves. Asplenium dalhousiae is placed in Ceterachopsis by pteridologists who believe it merits its own genus.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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