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Pellaea lyngholmii

(Lyngholm's Cliffbrake)

Overview

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Threatened

Threat status

Interesting Facts

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Common Names

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Common Names in English:

Lyngholm's Cliffbrake

Description

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Family Pteridaceae

Genera ca. 40, species ca. 1000 (13 genera, 90 sp: worldwide.

Considerable disagreement exists concerning the circumscription and proper name of this family . The taxa comprising the Pteridaceae in this treatment were assigned to the Sinopteridaceae and Pteridaceae by D. B . Lellinger (1985) and were included in five families by R. E. G. Pichi-Sermolli (1977). The broad concept followed here is similar (except for the exclusion of Ceratopteris ) to that espoused by R. M. Tryon and A. F. Tryon (1982), who applied the name Pteridaceae to the group. Until very recently, the newer name Adiantaceae was more commonly used.

As represented in North America, Pteridaceae comprise three major evolutionary lines (the adiantoids, the pteroids, and the cheilanthoids). Characteristics holding the family together include abaxial (usually submarginal ) sori that lack indusia or are protected by a reflexed or revolute leaf margin , spores that are usually globose-tetrahedral and trilete, and chromosome base numbers of 30 or 29 (rarely 27). The xeric-adapted members of the family (particularly the cheilanthoids) have undergone extensive parallel and convergent evolution, and they have frustrated attempts to produce a natural generic classification based on macromorphologic characteristics alone. Although some workers have aggregated species into a few large genera (e.g. , J. T. Mickel 1979b), most tend to recognize smaller segregate genera based on a combination of morphologic, chromosomal, and biochemical data. The latter approach seems to provide a more useful, evolutionarily informative classification and is the one adopted here. Aspidotis and Notholaena are maintained here as distinct from Cheilanthes, and three recently described genera ( Argyrochosma, Astrolepis, and Pentagramma ) have been incorporated into the treatment. The reasons for these changes in generic circumscription are discussed under the individual genera.[1]

Genus Pellaea

Plants usually on rock. Stems compact to long-creeping, ascending to horizontal, usually branched; scales brown to tan or often bicolored with dark, central stripe and lighter margins , linear-subulate to lanceolate (rarely ovate ), margins dentate , erose, or entire. Leaves monomorphic to somewhat dimorphic , clustered to widely scattered , 2--100 cm. Petiole brown, black, straw-colored, or gray, rounded , flattened or with single longitudinal groove adaxially, glabrous or pubescent , usually with a few scales at base , with single vascular bundle. Blade linear to ovate-deltate, 1--4-pinnate proximally, leathery or rarely somewhat herbaceous, abaxially glabrous, pubescent, or with hairlike scales scattered along costae, adaxially usually glabrous, dull , not striate ; rachis straight or flexuous . Ultimate segments of blade usually stalked and free from costae, elliptic , lanceolate to linear, usually more than 4 mm wide; base rounded, truncate , or cordate; stalks often lustrous and dark colored ; segment margins reflexed to form confluent , poorly defined, false indusia extending entire length of segment. Veins of ultimate segments free or rarely anastomosing, usually obscure , pinnately branched and divergent distally. False indusia greenish to whitish, narrow, clearly marginal , often concealing the sporangia. Sporangia scattered along veins near segment margins, containing 32 or 64 spores, often intermixed with glands , farina-producing. Spores brown to tan (rarely yellow), tetrahedral-globose, rugose or cristate , lacking prominent equatorial ridge . x = 29.

Species ca. 40 (15 in the flora ) : most in the Western Hemisphere, a small number in Asia, Africa, the Pacific Islands, and Australia.

Pellaea in the broad sense is a diverse , poorly defined assemblage of xeric-adapted ferns (A. R. Smith 1981) . Relationships among the North American, neotropical , and Eastern Hemisphere species are unclear, and it seems likely that the genus, as broadly construed by E. B . Copeland (1947) and R. M. Tryon and A. F. Tryon (1982), is polyphyletic. The species included here in Pellaea belong to a closely knit alliance that is usually recognized as a distinct section (sect. Pellaea ) . Although the inclusion of P . bridgesii in this group has been questioned (A. F. Tryon 1957), W. H. Wagner Jr. et al. (1983) have shown that the aberrant morphology of this species is simply an extreme expression of evolutionary trends commonly encountered in sect. Pellaea .

Among Western Hemisphere cheilanthoid ferns, species of Pellaea show clear morphologic, chromosomal, and biochemical affinities to Argyrochosma and members of the Cheilanthes alabamensis complex . In fact, the glabrous species of Argyrochosma ( A . jonesii and A . microphylla ) are commonly misidentified as Pellaea . These species are easily recognizable, however, because they have a combination of concolored stem scales and small ultimate segments (less than 4 mm wide) .[2]

Physical Description

Species Pellaea lyngholmii

Stems compact , ascending , stout, 5--10 mm diam.; scales uniformly brown or tan, linear-subulate, 0.1--0.3 mm wide, thin, margins entire to denticulate . Leaves somewhat dimorphic , sterile leaves shorter and less divided than fertile leaves, clustered on stem, 10--30 cm; croziers villous . Petiole dark brown to reddish purple, lustrous , rounded adaxially, without prominent articulation lines . Blade elongate-deltate to ovate , 2-pinnate proximally, 5--15 cm wide; rachis brown or reddish purple throughout, straight, often slightly flattened adaxially, sparsely villous with long, divergent hairs . Pinnae perpendicular to rachis or slightly ascending, not decurrent on rachis, usually with 7--15 ultimate segments; costae straight, 25--80 mm, usually longer than ultimate segments. Ultimate segments oblong-lanceolate, 7--25 mm, leathery, sparsely villous abaxially near midrib ; margins usually recurved on fertile segments, covering less than 1/2 abaxial surface, borders whitish, crenulate ; apex slightly mucronate . Veins of ultimate segments obscure . Sporangia long-stalked, containing 32 spores, not intermixed with farina-producing glands . Sporulating summer--fall. [source]

Pellaea lyngholmii is an apogamous tetraploid that arose through hybridization between P. atropurpurea and P. truncata (M. D. Windham 1993). It is most often confused with P. atropurpurea, from which P. lyngholmii differs in having sparsely villous rachises, smaller and more numerous ultimate segments, and spores usually more than 62 µm in diameter. [source]

Habit: Forb/herb

Habitat

Rocky slopes and ledges, usually on sandstone; 1200--1800 m (Ref. 102561).

Biology

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Reproduction

Duration: Perennial

Taxonomy

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Notes

Name Status: Accepted Name .

Last scrutiny: 15-Mar-2000

Similar Species

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Members of the genus Pellaea

ZipcodeZoo has pages for 30 species, subspecies, varieties, forms, and cultivars in this genus:

P. andromedifolia (Coffee Cliffbrake) · P. atropurpurea (Purple Cliffbrake) · P. brachyptera (Sierra Cliff-Brake) · P. breweri (Brewer's Cliff-Brake) · P. bridgesii (Bridges' Cliff-Brake) · P. cordifolia (Heartleaf Cliffbrake) · P. falcata (Australian Cliff Brake) · P. gastonyi (Gastony's Cliffbrake) · P. glabella (Dwarf Cliffbrake) · P. glabella occidentalis (Dwarf Cliffbrake) · P. glabella var. simplex (Dwarf Cliffbrake) · P. glabella subsp. missouriensis (Missouri Cliffbrake) · P. glabella subsp. occidentalis (Western Dwarf Cliffbrake) · P. glabella subsp. simplex (Smooth Cliffbrake) · P. glaciogena (Cliffbrake) · P. intermedia (Intermediate Cliffbrake) · P. lyngholmii (Lyngholm's Cliffbrake) · P. mucronata (Birdfoot Cliffbrake) · P. mucronata subsp. californica (California Cliffbrake) · P. ovata (Cliff Brake Fern) · P. rotundifolia (Button Fern) · P. ternifolia (Cliffbrake) · P. ternifolia subsp. arizonica (Arizonia Cliffbrake) · P. ternifolia subsp. villosa (Transpecos Cliffbrake) · P. truncata (Spiny Cliff-Brake) · P. villosa (Transpecos Cliffbrake) · P. viridis (Green Cliffbrake) · P. viridis var. macrophylla (Green Cliff Brake) · P. wrightiana (Wright Cliff-Brake) · P. x glaciogena (Cliffbrake)

More Info

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Further Reading

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Notes

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Contributors

Data Sources

Accessed through GBIF Data Portal December 30, 2007:

Identifiers

Footnotes

  1. Michael D. Windham "Pteridaceae". in Flora of North America Vol. 2. Oxford University Press. Online at EFloras.org. [back]
  2. Michael D. Windham "Pellaea". in Flora of North America Vol. 2. Oxford University Press. Online at EFloras.org. [back]
Last Revised: 7/15/2012