Asplenium rhizophyllum
Asplenium serratum
doradille ambulante, walking fern, walking spleenwort
American bird's-nest fern, new world bird's-nest fern, wild birdnest fern
not proliferous.
proliferous.
erect or ascending, usually unbranched;
scales dark brown throughout, narrowly deltate, 2–3 × (0.2–)0.5–1 mm, margins entire.
erect, unbranched;
scales brown throughout, narrowly lanceolate, 5–10 × 1–1.5 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.
vestigial.
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, oblanceolate, simple, (10–)20–40(–70) × 3–8 cm, thick, glabrous;
base gradually tapered;
margins entire to irregularly crenate;
apex attenuate, not rooting.
obscure, anastomosing to form areoles near midrib.
numerous, free, mostly immersed.
numerous, scattered somewhat irregularly over blade, often joined at vein junctures.
parallel to each other, nearly perpendicular to midrib.
64 per sporangium.
64 per sporangium.
green, dull, nearly glabrous.
green throughout, dull, glabrous.
= 72.
= 144.
Asplenium rhizophyllum
Asplenium serratum
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.)
Asplenium serratum is found rarely in southern peninsular Florida, where it is at the extreme edge of its tropical American range. This large simple-leaved spleenwort is called "American bird's-nest fern" because of its superficial resemblance to the Old World A. nidus Linnaeus, which is regularly grown in temperate conservatories. Asplenium serratum is unusual in having roots with abundant, matted hairs rather than scattered hairs as found in other species.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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