Asplenium adiantum-nigrum
Asplenium pinnatifidum
black spleenwort
lobed 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 to erect, frequently branched;
scales dark reddish brown, narrowly deltate, 3–5 × 0.3–0.5 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 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.
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 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.
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.
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.
free, evident.
free (rarely anastomosing), obscure.
1–numerous pairs per pinna [1–6 pairs per segment], on both basiscopic and acroscopic sides.
1–6(–40+) per segment, usually confluent with age.
64 per sporangium.
64 per sporangium.
greenish throughout or sometimes reddish brown proximally, lustrous, sparsely pubescent.
green, sometimes drying to tan, dull;
hairs on abaxial surface only, scattered, minute.
= 144.
= 144.
Asplenium adiantum-nigrum
Asplenium pinnatifidum
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.)
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.)
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