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
|
FL |
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 | ||
Name authority | Linnaeus: Mant. Pl. 1: 130. (1767) | E. P. St. John ex Small: Ferns S. E. States 173. (1938) |
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