Asplenium rhizophyllum
Asplenium ×heteroresiliens
doradille ambulante, walking fern, walking spleenwort
Morzenti's spleenwort, spleenwort
not proliferous.
not proliferous.
erect or ascending, usually unbranched;
scales dark brown throughout, narrowly deltate, 2–3 × (0.2–)0.5–1 mm, margins entire.
erect, rarely branched;
scales black throughout, linear-lanceolate, 1–3.5 × 0.1–0.4 mm, margins entire.
monomorphic but fertile leaves generally larger than sterile leaves.
monomorphic.
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.
black or purplish black throughout, lustrous, 1–2 cm, 1/5–1/10 length of blade;
indument of black filiform scales at base.
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.
linear to narrowly oblanceolate, 1-pinnate throughout, 5–15 × 1–2 cm, thick, glabrous;
base gradually tapered, apex acute, not rooting.
in 12–30 pairs, oblong to quadrangular;
medial pinnae 5–10 × 2–3 mm;
base with slight or prominent acroscopic auricle and often with basiscopic auricle;
margins usually shallowly crenulate, rarely ± entire;
apex acute to obtuse.
obscure, anastomosing to form areoles near midrib.
free, obscure.
numerous, scattered somewhat irregularly over blade, often joined at vein junctures.
1–5 pairs per pinna, on both basiscopic and acroscopic sides.
64 per sporangium.
32 per sporangium.
green, dull, nearly glabrous.
black or purplish black throughout, lustrous, glabrous or with a few scattered scales.
= 2n = 180 (apogamous).
= 72.
Asplenium rhizophyllum
Asplenium ×heteroresiliens
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.)
V. M. Morzenti (1966) studied the cytology and morphology of Asplenium × heteroresiliens and found it to be a pentaploid (5 x) of hybrid origin between A. resiliens (3 x) and A. heterochroum (4 x). The hybrid is intermediate in morphology between the parents, and it is difficult to separate from them. Misshapen spores mixed with large globose spores can usually be found on the same specimen.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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