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Published In: Species Plantarum 2: 1078. 1753. (1 May 1753) (Sp. Pl.) Name publication detailView in BotanicusView in Biodiversity Heritage Library

Project Name Data (Last Modified On 7/9/2009)
Acceptance : Accepted
Project Data     (Last Modified On 8/5/2009)


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1. Asplenium L. (spleenwort)

Plants perennial, homosporous. Rhizomes erect to short-creeping, compact, scaly, the scales clathrate (the endwalls colored, the centers transparent or nearly so). Leaves clustered, variously compound (simple or lobed elsewhere). Sporangia aggregated into sori on the undersurface of the leaf blades, extending along the veins, the indusium membranous, attached along 1 side. Spores 32 or 64 per sporangium, monolete, 25–60 mm long, black. Gametophytes green, flat, heart-shaped to kidney-shaped, often with stalked glands. About 700 species, worldwide.

Most of the Missouri species of this genus belong to a group known as the “Appalachian Asplenium Complex,” which is among the most intensively studied groups of ferns in the world. The genus is famous for its high levels of interspecific hybridization, with sterile, primary hybrids recovering fertility through a process of chromosomal doubling. Although relatively few of the primary hybrids have been reported from Missouri, they should be looked for in the field in areas where two or more species grow together. Hybrid spleenworts can usually be recognized by their unusual, irregular leaf division pattern, with adjacent pinnae or lobes unequal in size.


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1 Leaf blades simple, deeply pinnately lobed or unlobed except for a pair of basal auricles; the tips long-attenuate (2)
+ Leaf blades 1–3 times compound (3)
2 (1) Leaf blades deeply, pinnately lobed 3 Asplenium pinnatifidum
+ Leaf blades unlobed except for a pair of basal auricles, these rounded or attenuate 6 Asplenium rhizophyllum
3 (1) Petioles green, at least in the upper 1/2; leaf blades 2–3 times pinnately compound (4)
+ Petioles reddish brown to black their entire length; leaf blades 1–2 times pinnately compound (5)
4 (3) Petioles green except at the very base; pinnules spathulate to nearly diamond-shaped 7 Asplenium ruta-muraria
+ Petioles green in the upper 1/2–2/3, dark brown basally; pinnules linear to oblong or ovate 2 Asplenium montanum
5 (3) Lower pinnae compound or deeply lobed, at least toward the base 1 Asplenium bradleyi
+ Lower pinnae toothed or shallowly lobed, sometimes auriculate at the base of the upper margin (6)
6 (5) Pinnae not auriculate, oblong to ovate or wedge-shaped, the median pinnae 4–7 mm long 8 Asplenium trichomanes L. subsp. trichomanes
+ At least the median pinnae auriculate (with small outgrowths of tissue) at the base of the upper margin (sometimes also the lower margin), oblong to linear-lanceolate, (5–)7–35 mm long (7)
7 (6) Leaves somewhat dimorphic, the sterile leaves prostrate to arching with shorter pinnae, the fertile leaves erect with longer pinnae; petioles and rachises dark brown; pinnae alternate, the bases mostly overlapping the rachis 4 Asplenium platyneuron
+ Leaves monomorphic; petioles and rachises black; pinnae opposite to subopposite, the bases not overlapping the rachis 5 Asplenium resiliens
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