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Astrolepis windhamii

(Windham's Scaly Cloakfern)

Overview

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Vulnerable

Threat status

Interesting Facts

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Common Names

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Common Names in English:

Windham's Scaly Cloakfern, Windhams Scaly Cloakfern

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 Astrolepis

Plants usually on rock. Stems compact to short-creeping, erect to ascending , sparingly branched; scales tan to chestnut brown, concolored to weakly bicolored , linear-attenuate, margins ciliate-dentate to entire. Leaves monomorphic , densely clustered, 7--130 cm. Petiole dull chestnut brown or straw-colored, rounded adaxially, sparsely to densely covered with scales, with 2 vascular bundles . Blade linear to linear-oblong, 1-pinnate to pinnate-pinnatifid, leathery, abaxially covered with overlapping, lanceolate to ovate , ciliate scales with underlying layer of stellate scales, adaxially sparsely to densely covered with stellate or coarsely ciliate scales, often glabrescent when mature , dull, not striate ; rachis straight. Ultimate segments (pinnae) stalked to subsessile , free from axis, ovate, oblong or elongate-deltate, cordate to subcordate or rarely truncate at base , usually more than 4 mm wide; segment margins plane , undifferentiated, not recurved to form false indusia. Veins of ultimate segments obscure , pinnately branched and divergent distally. False indusium absent. Sporangia scattered along veins near pinna margins (often clustered near notches between pinna lobes ), containing 32 or 64 spores, not intermixed with farina-producing glands . Spores light to dark brown, tetrahedral-globose, rugose , lacking prominent equatorial ridge . Gametophytes glabrous . x = 29.

Species ca. 8: North America, Mexico, West Indies, Central America, South America.

The species of Astrolepis have traditionally been assigned to either Notholaena (R. M. Tryon 1956) or Cheilanthes (J. T. Mickel 1979b; R. M. Tryon and A. F. Tryon 1982). Recent biosystematic analyses by D. M. Benham and M. D. Windham (1992) indicate, however, that the star-scaled cloak ferns form a distinctive, monophyletic group worthy of generic recognition. The combination of a chromosome base number of x = 29, pinnate leaves, two vascular bundles in the petioles, unique stellate or coarsely ciliate scales on the adaxial blade surface, and other characteristics separate Astrolepis from related genera.[2]

Physical Description

Species Astrolepis windhamii

Stems compact to short-creeping; stem scales uniformly tan or somewhat darker near base , to 15 mm, margins ciliate-dentate to entire. Leaves 10--50 cm. Blade pinnate-pinnatifid, pinna pairs 20--45. Pinnae ovate to deltate, largest 7--15 mm, usually symmetrically lobed , lobes 6--11, broadly rounded , separated by shallow sinuses; abaxial scales concealing surface, lanceolate, usually 1--1.5 mm, ciliate with coarse marginal projections; adaxial scales sparse, mostly persistent , elongate , usually stellate , attached at base, body 2--4 cells wide. Sporangia containing 32 spores. n = 2 n = 87, apogamous. Sporulating summer--fall. [source]

Recent isozyme analyses (D. M. Benham 1989) indicate that Astrolepis windhamii is an apogamous allotriploid that contains three different genomes, one each from A. sinuata, A. cochisensis, and an unnamed Mexican taxon related to A. crassifolia. Because of this genomic constitution , Astrolepis windhamii tends to bridge the morphologic gap between A. sinuata and A. integerrima, which is itself a hybrid between A. cochisensis and the unnamed Mexican species. Although the features that separate these taxa are subtle, the pinna lobing and scale characteristics of A. windhamii mentioned in the key adequately distinguish them in most cases. [source]

Habit: Forb/herb

Habitat

Rocky hillsides and cliffs ; occurring on calcareous and noncalcareous substrates; 1200--2100 m [3].

Biology

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Reproduction

Duration: Perennial

Taxonomy

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Notes

Publishing author : D.M.Benham Publication : Amer. Fern J. 82: 60, fig. 1 1992

Similar Species

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Members of the genus Astrolepis

ZipcodeZoo has pages for 8 species, subspecies, varieties, forms, and cultivars in this genus:

A. cochisensis arizonica (Cochise Scaly Cloakfern) · A. cochisensis chihuahuaensis (Chihuahua Scaly Cloakfern) · A. cochisensis subsp. arizonica (Arizona Scaly Cloakfern) · A. integerrima (Astrolepis) · A. sinuata (Wavy Scaly Cloakfern) · A. sinuata mexicana (Cochise Scaly Cloakfern) · A. sinuata subsp. mexicana (Mexican Scaly Cloakfern) · A. windhamii (Windham's Scaly Cloakfern)

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 February 28, 2008:

Identifiers

Footnotes

  1. Michael D. Windham "Pteridaceae". in Flora of North America Vol. 2. Oxford University Press. Online at EFloras.org. [back]
  2. Dale M. Benham, Michael D. Windham "Astrolepis". in Flora of North America Vol. 2. Oxford University Press. Online at EFloras.org. [back]
  3. "Astrolepis windhamii". in Flora of North America Vol. 2. Oxford University Press. Online at EFloras.org. [back]
Last Revised: 7/15/2012