Argyrochosma lumholtzii

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Argyrochosma lumholtzii
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Plantae
Clade: Tracheophytes
Division: Polypodiophyta
Class: Polypodiopsida
Order: Polypodiales
Family: Pteridaceae
Genus: Argyrochosma
Species:
A. lumholtzii
Binomial name
Argyrochosma lumholtzii
Synonyms
  • Hemionitis lumholtzii(Maxon & Weath.) Christenh.
  • Notholaena lumholtziiMaxon & Weath.

Argyrochosma lumholtzii is a rare fern in the family Pteridaceae known from Sonora, Mexico. It is quite similar to Jones' false cloak fern, but has black leaf axes and a less highly divided leaf. First described as a species in 1939, honoring the explorer Carl Sofus Lumholtz, it was transferred to the new genus Argyrochosma (the "false cloak ferns") in 1987, recognizing their distinctness from the "cloak ferns" ( Notholaena sensu stricto ).

Contents

Description

Argyrochosma lumholtzii is a small fern. Its rhizome is compact and upright. It bears linear [1] or linear-ligulate (straplike) [2] scales 4 to 5 millimeters (0.2 to 0.2 in) long, long-acuminate at the tip, [2] somewhat twisted, of a uniform orange-brown [1] or reddish-brown color, [2] with entire (toothless) margins. [1]

The fronds arise in clumps from the rhizome. They are 7 to 15 centimeters (2.8 to 5.9 in) long from the base to the tip of the leaf. [1] [2] Of this length, about two-thirds is made up by the stipe (the stalk of the leaf, below the blade), which is shiny and round, hairless, and black in color. [1] [2]

The leaf blades are deltate-lanceolate to deltate-ovate. [1] [2] They are bipinnate (cut into pinnae and pinnules), becoming pinnate (but not pinnate-pinntifid) in the upper part of the blade. [2] The rachis (leaf axis) is round (rather than flattened) straight, and hairless, [1] and is similar to the stipe in color. [2] Each blade bears 6 to 8 pairs of pinnae, [1] which are widely spaced and alternate to nearly opposite on the rachis. [2] These are divided into pinnules, which are orbicular (circular) or slightly oblong to nearly cordate (heart-shaped), without a clear joint at the stalk; they are widely separated from one another. They are typically 3 to 4 millimeters (0.1 to 0.2 in) across, and have entire margins. The terminal pinnules are deltate. [1] The leaf tissue is gray-green in color, leafy or slightly leathery in texture, and lacks hairs. [1] Unlike many species of Argyrochosma , the underside of the leaf lacks a coating of farina (powder). [3]

The sori lie along the veins, in the portions closest to the edge of the leaf, [1] extending over roughly one-third to one-half of the vein. [2] The leaf edges are not modified into false indusia; they are sometimes, thought not always, slightly curved under. Each sporangium bears 64 spores, [1] [2] indicating that it is a sexual diploid species. [4]

It is most similar to Argyrochosma jonesii , but can be distinguished from it by its black (rather than brownish) leaf axes, and the bipinnate (rather than bi- to tripinnate) division of the leaf. [5]

Taxonomy

It was first described by William Ralph Maxon and Charles Alfred Weatherby in 1939 as Notholaena lumholtzii. It was named in honor of Carl Sofus Lumholtz, as the type material was collected in Sonora on his expedition to Mexico. [6] They placed it within a group of ferns closely related to Notholaena nivea. Both Edwin Copeland and Weatherby suggested in the 1940s that this group of ferns might represent a distinct genus of its own. [7] This was finally addressed in 1987 by Michael D. Windham, who was carrying out phylogenetic studies of these genera. He elevated Notholaena sect. Argyrochosma to become the genus Argyrochosma , [8] and transferred this species to that genus as A. lumholtzii. [9] In 2018, Maarten J. M. Christenhusz transferred the species to Hemionitis as H. lumholtzii, as part of a program to consolidate the cheilanthoid ferns into that genus. [10]

Phylogenetic studies have shown that A. lumholtzii is a sister species to A. jonesii; these two species form a clade sister to another clade containing A. formosa and A. microphylla. [11] All four species lack farina, and their common ancestor is hypothesized to have diverged from the ancestor of the rest of the genus before farina production developed in the latter. [12]

Distribution and habitat

Argyrochosma lumholtzii is quite rare, known only from a few locations in Sonora. [1]

The habitat of the original collections made during the Lumholtz expedition was not recorded. [5]

Notes and references

Related Research Articles

<i>Notholaena</i> Genus of ferns

Notholaena, cloak fern, is a genus of ferns in the Cheilanthoideae subfamily of the Pteridaceae. Ferns of this genus are mostly epipetric or occurring in coarse, gravelly soils, and are most abundant and diverse in the mountain ranges of warm arid or semiarid regions. They typically have a creeping or erect rhizome and leaves that are pinnatifid to pinnate-pinnatifid with marginal sori protected by a false indusium formed from the reflexed margin of the leaf. Members of Notholaena also have a coating of whitish or yellowish farina on the surfaces of the leaves. The farina is often limited to the abaxial (lower) leaf surface, but may occur on the adaxial (upper) leaf surface as well. Members of the related Pentagramma genus have a similar lower leaf-surface farina.

<i>Argyrochosma</i> Genus of ferns in the family Pteridaceae

Argyrochosma is a genus of ferns known commonly as false cloak ferns. The genus is included in the Cheilanthoideae subfamily of the Pteridaceae. Species now in this genus were previously treated as members of related genera Notholaena or Pellaea but were segregated into their own genus in 1987. These ferns, of which there are about 20 species, are mostly native to the Americas, from North to South and including the Caribbean, while one species, A. connectens, is known from Sichuan, China. They are commonly found growing in cracks between rocks. Their leaves are generally shorter than 40 cm (16 in) and have rounded bluish or grayish green segments. Often the lower surface of the segments is coated in a white dust, and the sporangia contain brown spores.

<i>Argyrochosma jonesii</i> Species of fern in the family Pteridaceae

Argyrochosma jonesii, known as Jones' false cloak fern, is a species of fern native to the southwestern United States and Sonora, Mexico. It grows on calcareous rocks, and has small, finely-divided leaves with a leathery texture and dark axes connecting the leaf segments. Unlike many members of Argyrochosma, it does not secrete white powder on the underside of its leaves. First described as a species in 1917, it was transferred to the new genus Argyrochosma in 1987, recognizing their distinctness from the "cloak ferns".

<i>Argyrochosma nivea</i> Species of fern in the family Pteridaceae

Argyrochosma nivea is an Andean fern species in the family Pteridaceae.

Myriopteris aemula, the Texas lip fern or rival lip fern, is a moderately-sized fern of Texas and Mexico, a member of the family Pteridaceae. Unlike many members of its genus, its leaves have a few hairs on upper and lower surfaces, or lack them entirely. One of the cheilanthoid ferns, it was usually classified in the genus Cheilanthes as Cheilanthes aemula until 2013, when the genus Myriopteris was again recognized as separate from Cheilanthes. It typically grows on limestone rock.

<i>Argyrochosma dealbata</i> Species of fern in the family Pteridaceae

Argyrochosma dealbata, the powdery false cloak fern, is a small fern endemic to the central and southern United States. It grows on calcareous rocks, such as limestone. Its leaves are highly divided, with leaf segments joined by shiny, chestnut-brown axes, and their undersides are coated with white powder, giving the fern its name. First described as a species in 1814, it was transferred to the new genus Argyrochosma in 1987, recognizing their distinctness from the "cloak ferns".

Argyrochosma connectens is a small cheilanthoid fern endemic to Sichuan, China. It is the only member of its genus known from Asia. Relatively rare, it is found growing in the crevices of limestone rocks in hot, dry valleys. The species was long classified in the genus Pellaea, but after a phylogenetic study in 2015 was transferred to Argyrochosma.

Argyrochosma delicatula is a fern known from northeastern Mexico. It grows in rocky habitats, either in sun or in shade, and is distinguished from similar species by the presence of pale yellow powder on the underside of its leaves. First described as a species in 1939, it was transferred to the new genus Argyrochosma in 1987, recognizing their distinctness from the "cloak ferns".

<i>Argyrochosma peninsularis</i> Species of fern in the family Pteridaceae

Argyrochosma peninsularis is a fern endemic to Baja California Sur. It grows in dry, rocky places. First described as a species in 1939, it was transferred to the new genus Argyrochosma in 1987, recognizing their distinctness from the "cloak ferns". A dusting of powdery material and the presence of occasional scales on the central axis of its leaves help distinguish it from related species.

Argyrochosma pallens is a fern endemic to Mexico. It has narrow, divided leaves with brown axes; the leaves are dusted with white powder above and coated in it below. First described as a species in 1956, it was transferred to the new genus Argyrochosma in 1987, recognizing their distinctness from the "cloak ferns".

Argyrochosma chilensis is a fern endemic to the Juan Fernández Islands off the coast of Chile. It has leathery, thrice-divided leaves with dark brown axes; the leaves are coated with white powder below. First described as a species in 1853, it was transferred to the new genus Argyrochosma in 1987, recognizing their distinctness from the "cloak ferns".

Argyrochosma stuebeliana is a fern endemic to Peru. Its highly divided, leathery leaves are coated with white powder on their under surface. It was originally described as a variety of Argyrochosma dealbata in 1909, based on a single leaf collected by Alphons Stübel, whom its name honors. In 1961, it was recognized as a distinct species, distinguished from similar members of the genus largely by its round leaf segments. It was transferred to the new genus Argyrochosma in 1987, recognizing their distinctness from the "cloak ferns".

<i>Argyrochosma fendleri</i> Species of fern in the family Pteridaceae

Argyrochosma fendleri, Fendler's false cloak fern, is a fern known from the western United States and northwestern Mexico. It grows in rocky habitats, and is distinguished from other members of the genus by its zig-zag leaf axes. Like many species in the genus, it bears white powder on the underside of its leaves. First described as a species in 1851, it was transferred to the new genus Argyrochosma in 1987, recognizing their distinctness from the "cloak ferns".

Argyrochosma incana, the hairy false cloak fern, is a fern known from the southwestern United States through Mexico to Guatemala, and from a disjunct population in the Dominican Republic. It grows on rocky slopes and steep banks, often in forests. Like many of the false cloak ferns, it bears white powder on the underside of its leaves. First described as a species in 1825, it was transferred to the new genus Argyrochosma in 1987, recognizing their distinctness from the "cloak ferns".

Argyrochosma palmeri is a fern endemic to Mexico. It has narrow, divided leaves with black axes; the leaves are coated in white powder below, and sparsely dusted or free of it above. First described as a species in 1887, it was transferred to the new genus Argyrochosma in 1987, recognizing their distinctness from the "cloak ferns".

Argyrochosma pilifera is a fern endemic to Mexico. It has lance-shaped, divided leaves with dark purple axes; the undersides of the leaves are coated in white powder. First described as a species in 1956, it was transferred to the new genus Argyrochosma in 1987, recognizing their distinctness from the "cloak ferns".

<i>Argyrochosma formosa</i> Species of fern in the family Pteridaceae

Argyrochosma formosa is a fern known from eastern and central Mexico and Guatemala. It grows on rocky slopes, particularly on limestone. Unlike many members of the genus, it lacks white powder on the underside of its leaves. First described as a species in 1842, it was transferred to the new genus Argyrochosma in 1987, recognizing their distinctness from the "cloak ferns".

<i>Argyrochosma limitanea</i> Species of fern in the family Pteridaceae

Argyrochosma limitanea, the southwestern false cloak fern, is a species of fern native to the southwestern United States and Sonora, Mexico. It grows on calcareous rocks, and has small, finely-divided leaves with a leathery texture, dark axes connecting the leaf segments, and a heavy coating of white powder on the undersurface. It reproduces apogamously; two subspecies are recognized, which may have originated independently through the hybridization of other taxa not yet discovered. First described as a species in 1919, it was transferred to the new genus Argyrochosma in 1987, recognizing their distinctness from the "cloak ferns".

<i>Argyrochosma microphylla</i> Species of fern in the family Pteridaceae

Argyrochosma microphylla, the small-leaf false cloak fern, is a species of fern native to New Mexico, Texas and northern Mexico. It grows on limestone rocks and cliffs, and has finely-divided leaves with small leaf segments, often folded in half when dry, which lack the white powder present on the leaf underside of many related species. First described as a species in 1869, it was transferred to the new genus Argyrochosma in 1987, recognizing their distinctness from the "cloak ferns".

Myriopteris cinnamomea is a Central American fern. It is very similar to M. mickelii of southern Mexico and to other species in the "alabamensis clade" of Myriopteris. It is modestly sized, with leaves not more than 30 centimeters (12 in) long. They are divided into pinnae, which in turn are divided into lobed pinnules, and covered with pale brown hairs on the underside.

References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 13 Mickel & Smith 2004, p. 68.
  2. 1 2 3 4 5 6 7 8 9 10 11 Tryon & Weatherby 1956, p. 84.
  3. ↑ Mickel & Smith 2004, p. 64.
  4. ↑ Sigel et al. 2011, p. 555.
  5. 1 2 Mickel & Smith 2004, p. 69.
  6. ↑ Maxon & Weatherby 1939, pp. 16–17.
  7. ↑ Windham 1987, p. 37.
  8. ↑ Windham 1987, p. 38.
  9. ↑ Windham 1987, p. 40.
  10. ↑ Christenhusz, Fay & Byng 2018, p. 17.
  11. ↑ Sigel et al. 2011, p. 558.
  12. ↑ Sigel et al. 2011, p. 559.

Works cited

  • Christenhusz, Maarten J. M.; Fay, Michael F.; Byng, James W. (2018). Plant Gateway's the Global Flora: A practical flora to vascular plant species of the world. Vol. 4. ISBN   978-0-9929993-9-1.
  • Maxon, W. R.; Weatherby, C. A. (1939). "Some species of Notholaena, new and old". Contributions from the Gray Herbarium. 127 (127): 3–17. doi: 10.5962/p.336228 . JSTOR   41764097.
  • Mickel, John T.; Smith, Alan R. (2004). The Pteridophytes of Mexico. Memoirs of the New York Botanical Garden. Vol. 88. Bronx, New York: New York Botanical Garden. ISBN   978-0-89327-488-7.
  • Sigel, Erin M.; Windham, Michael D.; Huiet, Layne; Yatskievych, George; Pryer, Kathleen M. (2011). "Species Relationships and Farina Evolution in the Cheilanthoid Fern Genus Argyrochosma (Pteridaceae)". Systematic Botany. 36 (3): 554–564. doi:10.1600/036364411X583547. JSTOR   23028975.
  • Tryon, Rolla M.; Weatherby, Una F. (1956). "A revision of the American species of Notholaena". Contributions from the Gray Herbarium of Harvard University (179): 1–106. doi: 10.5962/p.336378 . JSTOR   41764632.
  • Windham, Michael D. (1987). "Argyrochosma, a new genus of cheilanthoid ferns". American Fern Journal. 77 (2): 37–41. doi:10.2307/1547438. JSTOR   1547438.
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