FNA: Asplenium monanthes vs. Asplenium plenum

	Asplenium monanthes	Asplenium plenum
	single-sorus fern, single-sorus spleenwort	ruffled spleenwort
Roots	not proliferous.	proliferous.
Stems	erect, unbranched; scales black with lighter margins, linear-lanceolate, 3–6 × 0.4–0.8 mm, margins entire.	erect, unbranched; scales blackish throughout, narrowly deltate, 0.4–1.1 × 0.3–0.7 mm, margins entire to denticulate.
Leaves	monomorphic.	monomorphic.
Petiole	reddish brown throughout, lustrous, 1–12(–20) cm, 1/3–1/10 length of blade; indument of black filiform scales.	blackish throughout, dull, 2–6(–10) cm, 1/4–2/5 length of blade; indument absent.
Blade	linear, 1-pinnate throughout, 5–25(–40) × 1–2.5(–3) cm, thick, glabrous; base gradually tapered; apex acute, not rooting.	lanceolate, 1–2-pinnate, (4–)8–12(–15) × 1.5–5 cm, thin, glabrous; base not tapered; apex gradually narrowing.
Pinnae	in 10–40 pairs, oblong to quadrangular, somewhat asymmetric; medial pinnae 4–15 × 2–5 mm; base rounded to cuneate; margins crenulate or ± entire; apex obtuse.	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, obscure.	free, not conspicuous.
Sori	1(–3) per pinna, only on basiscopic side.	mostly 1 per segment, 1–3 mm.
Spores	32 per sporangium.	mostly abortive, some viable.
Rachis	reddish brown throughout, lustrous, glabrous.	mostly green except occasionally blackish at base, dull, glabrous.
n	= 2n = 108 (apogamous).
Pinnules		linear to oblong, 4–10 mm; apex mostly notched.
2n		= 144.

	Asplenium monanthes	Asplenium plenum
Habitat	Rock	Limestone rocks in shaded forests
Elevation	50–1000 m (200–3300 ft)	0–50 m (0–200 ft)
Distribution	AL; AZ; NC; SC; HI; Mexico; Central America; West Indies in Hispaniola; Jamaica; South America to n Argentina; Africa including Madagascar; Madeira; Réunion; Tristan da Cunha [WildflowerSearch map] [BONAP county map]	FL [BONAP county map]
Discussion		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. adiantum-nigrum, A. adulterinum, A. auritum, A. bradleyi, A. cristatum, A. dalhousiae, A. ebenoides, A. exiguum, A. heterochroum, 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
Name authority	Linnaeus: Mant. Pl. 1: 130. (1767)	E. P. St. John ex Small: Ferns S. E. States 173. (1938)
Web links	WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search	WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Asplenium plenum

single-sorus fern, single-sorus spleenwort

ruffled spleenwort

Roots

not proliferous.

proliferous.

Stems

erect, unbranched;

scales black with lighter margins, linear-lanceolate, 3–6 × 0.4–0.8 mm, margins entire.

erect, unbranched;

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

Leaves

monomorphic.

Petiole

reddish brown throughout, lustrous, 1–12(–20) cm, 1/3–1/10 length of blade;

indument of black filiform scales.

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

indument absent.

Blade

linear, 1-pinnate throughout, 5–25(–40) × 1–2.5(–3) cm, thick, glabrous;

base gradually tapered;

apex acute, not rooting.

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

base not tapered;

apex gradually narrowing.

Pinnae

in 10–40 pairs, oblong to quadrangular, somewhat asymmetric;

medial pinnae 4–15 × 2–5 mm;

base rounded to cuneate;

margins crenulate or ± entire;

apex obtuse.

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, obscure.

free, not conspicuous.

Sori

1(–3) per pinna, only on basiscopic side.

mostly 1 per segment, 1–3 mm.

Spores

32 per sporangium.

mostly abortive, some viable.

Rachis

reddish brown throughout, lustrous, glabrous.

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

= 2n = 108 (apogamous).

Pinnules

linear to oblong, 4–10 mm;

apex mostly notched.

= 144.

Asplenium plenum

Habitat

Rock

Limestone rocks in shaded forests

Elevation

50–1000 m (200–3300 ft)

0–50 m (0–200 ft)

Distribution

AL; AZ; NC; SC; HI; Mexico; Central America; West Indies in Hispaniola; Jamaica; South America to n Argentina; Africa including Madagascar; Madeira; Réunion; Tristan da Cunha

[WildflowerSearch map]

[BONAP county map]

Discussion

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.

Parent taxa

Aspleniaceae > Asplenium

Sibling taxa

A. abscissum, A. adiantum-nigrum, A. adulterinum, A. auritum, A. bradleyi, A. cristatum, A. dalhousiae, A. ebenoides, A. exiguum, A. heterochroum, 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

Name authority

Linnaeus: Mant. Pl. 1: 130. (1767)

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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Asplenium monanthes

Asplenium plenum

Asplenium monanthes

Asplenium plenum