Asplenium adiantum-nigrum
Asplenium rhizophyllum
black spleenwort
doradille ambulante, walking fern, walking 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 or ascending, usually unbranched;
scales dark brown throughout, narrowly deltate, 2–3 × (0.2–)0.5–1 mm, margins entire.
monomorphic.
monomorphic but fertile leaves generally larger than sterile leaves.
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.
reddish brown at base, becoming green distally, dull but sometimes lustrous at base, 0.5–12 cm, 0.1–1.5 times length of blade;
indument of dark brown, narrowly deltate scales at base, of minute, club-shaped hairs distally.
deltate, 2–3-pinnate, 2.5–10 × 2–6.5 cm, thick, hairs dark, scattered, minute;
base truncate;
apex acute to acuminate, not rooting.
highly variable in size and shape, even on 1 plant, narrowly deltate to linear-lanceolate, simple, 1–30 × 0.5–5 cm, leathery, sparsely pubescent, hairs more numerous abaxially than adaxially;
blade base cordate, auriculate, or occasionally hastate, auricles rarely attenuate and radicant;
margins entire to sinuate, rarely irregularly incised;
apex rounded to very long-attenuate and, if attenuate, generally rooting at tip.
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.
obscure, anastomosing to form areoles near midrib.
1–numerous pairs per pinna [1–6 pairs per segment], on both basiscopic and acroscopic sides.
numerous, scattered somewhat irregularly over blade, often joined at vein junctures.
64 per sporangium.
64 per sporangium.
greenish throughout or sometimes reddish brown proximally, lustrous, sparsely pubescent.
green, dull, nearly glabrous.
= 144.
= 72.
Asplenium adiantum-nigrum
Asplenium rhizophyllum
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 rhizophyllum, a diploid species, is morphologically very distinctive within Asplenium and is segregated by many authors, along with its sister species A. ruprechtii Kurata of eastern Asia, into the genus Camptosorus Link. Proliferations arising from leaf tips result in the formation of clonal patches, often dense and extensive, on the mossy boulders and ledges where it typically grows. Naturally occurring sterile hybrids are known with A. platyneuron (these and their fertile allotetraploid derivatives are both referred to A. ebenoides), A. ruta-muraria (A. × inexpectatum E. L. Braun ex C. V. Morton), A. trichomanes subsp. trichomanes [A. × shawneense (R. C. Moran) H. E. Ballard], and A. ebenoides. In addition, the allotetraploid A. pinnatifidum is derived from the hybrid A. montanum × rhizophyllum; the sterile diploid hybrid is unknown.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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