Flora of North America species comparison

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Asplenium adiantum-nigrum

Asplenium plenum

black spleenwort

ruffled spleenwort
Roots

not proliferous.

proliferous.
Stems

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 blackish throughout, narrowly deltate, 0.4–1.1 × 0.3–0.7 mm, margins entire to denticulate.
Leaves

monomorphic.

monomorphic.
Petiole

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.

blackish throughout, dull, 2–6(–10) cm, 1/4–2/5 length of blade;

indument absent.
Blade

deltate, 2–3-pinnate, 2.5–10 × 2–6.5 cm, thick, hairs dark, scattered, minute;

base truncate;

apex acute to acuminate, not rooting.

lanceolate, 1–2-pinnate, (4–)8–12(–15) × 1.5–5 cm, thin, glabrous;

base not tapered;

apex gradually narrowing.
Pinnae

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.

in (5–)10–20(–25) pairs, oblong-deltate, 1–3.5 × 0.5–1.8 cm;

base excavate on basiscopic side;

apex pointed.
Veins

free, evident.

free, not conspicuous.
Sori

1–numerous pairs per pinna [1–6 pairs per segment], on both basiscopic and acroscopic sides.

mostly 1 per segment, 1–3 mm.
Spores

64 per sporangium.

mostly abortive, some viable.
Rachis

greenish throughout or sometimes reddish brown proximally, lustrous, sparsely pubescent.

mostly green except occasionally blackish at base, dull, glabrous.
Pinnules

linear to oblong, 4–10 mm;

apex mostly notched.
2n

= 144.

= 144.

Asplenium adiantum-nigrum

Asplenium plenum
Habitat Cliffs Limestone rocks in shaded forests
Elevation 1675–2300 m (5500–7500 ft) 0–50 m (0–200 ft)
Distribution
from FNA
AZ; CO; UT; Eurasia; Africa
[BONAP county map]
from FNA
FL
[BONAP county map]
Discussion

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 plenum occurs with its parents on limestone rocks in shaded forests and is known only from Florida, although it could occur in the Antilles, Central America, and South America (D. B. Lellinger 1981). It is noteworthy for constituting one of the first known examples of backcrossing and formation of a new taxon by unreduced spores from a sterile hybrid. According to V. M. Morzenti (1967) and G. J. Gastony (1986), hybridization between A. abscissum and A. verecundum produced A. × curtissii. An unreduced spore of the hybrid gave rise to a 3 x gametophyte. This gametophyte produced a 3 x sperm that backcrossed with an x egg of A. abscissum producing the 4 x allotetraploid, A. plenum, that is not only capable of propagation by minute root proliferations like those of the parents but also to some extent by spores. This complex hypothesis was confirmed by electrophoretic comparisons of the plants involved (G. J. Gastony 1986).

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 2. FNA vol. 2.
Parent taxa Aspleniaceae > Asplenium Aspleniaceae > Asplenium
Sibling taxa
A. abscissum, A. adulterinum, A. auritum, A. bradleyi, A. cristatum, A. dalhousiae, A. ebenoides, A. exiguum, A. heterochroum, A. monanthes, A. montanum, A. palmeri, A. pinnatifidum, A. platyneuron, A. plenum, A. pumilum, A. resiliens, A. rhizophyllum, A. ruta-muraria, A. scolopendrium, A. septentrionale, A. serratum, A. trichomanes, A. trichomanes-dentatum, A. trichomanes-ramosum, A. verecundum, A. vespertinum, A. ×biscayneanum, A. ×curtissii, A. ×heteroresiliens
A. abscissum, A. adiantum-nigrum, A. adulterinum, A. auritum, A. bradleyi, A. cristatum, A. dalhousiae, A. ebenoides, A. exiguum, A. heterochroum, A. monanthes, A. montanum, A. palmeri, A. pinnatifidum, A. platyneuron, A. pumilum, A. resiliens, A. rhizophyllum, A. ruta-muraria, A. scolopendrium, A. septentrionale, A. serratum, A. trichomanes, A. trichomanes-dentatum, A. trichomanes-ramosum, A. verecundum, A. vespertinum, A. ×biscayneanum, A. ×curtissii, A. ×heteroresiliens
Synonyms A. andrewsii, A. chihuahuense, A. dubiosum
Name authority Linnaeus: Sp. Pl. 2: 1081. (1753) E. P. St. John ex Small: Ferns S. E. States 173. (1938)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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