Argyrochosma jonesii

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Argyrochosma jonesii
Argyrochosma jonesii 2.jpg
Argyrochosma jonesii growing on a cliff
Status TNC G4.svg
Apparently Secure  (NatureServe) [1]
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Plantae
Clade: Tracheophytes
Division: Polypodiophyta
Class: Polypodiopsida
Order: Polypodiales
Family: Pteridaceae
Genus: Argyrochosma
Species:
A. jonesii
Binomial name
Argyrochosma jonesii
Synonyms
  • Cheilanthes jonesii(Maxon) Munz
  • Hemionitis jonesii(Maxon) Christenh.
  • Notholaena jonesiiMaxon
  • Pellaea jonesii(Maxon) C.V.Morton

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 (the "false cloak ferns") in 1987, recognizing their distinctness from the "cloak ferns" ( Notholaena sensu stricto ).

Contents

Description

The rhizome is short and horizontal, with leaves closely spaced. [2] It bears linear [3] or linear-subulate, [4] uniformly colored, brown or reddish-brown scales, [3] sometimes nearly black in color, [5] with entire (toothless) margins [3] and a thin texture. [4] They are 5 to 7 millimeters (0.2 to 0.3 in) long and 0.3 millimeters (0.01 in) wide. [2]

The leaves range from 4 to 15 centimeters (1.6 to 5.9 in) long, [2] [5] and arise in clumps. [2] [4] The stipe (the stalk of the leaf, below the blade) is chestnut brown or reddish-brown to dark brown, rounded and hairless, [2] [4] [5] [3] and 0.75 to 1.5 millimeters (0.030 to 0.059 in) in diameter. [5] It is typically 2 to 6 centimeters (0.79 to 2.4 in) long, [3] making up about one-half to two-thirds of the total length of the leaf. [2] The leaf blade is ovate to lanceolate, and ranges from bipinnate (cut into pinnae and pinnules) to tripinnate (with pinnules cut into pinnulets) at the base, where it is most divided. [2] [4] [5] [3] It is not reduced in width at the base. [4] The blade measures from 3 to 7 centimeters (1 to 3 in) long and 0.8 to 3 centimeters (0.3 to 1 in) wide. [3] The base is obtuse (blunt), while the tip is acute (pointed). [3] The rachis (leaf axis) is rounded or slightly flattened on the upper side, sometimes even shallowly grooved, [2] and dark in color, as are the axes of the leaf segments. The color continues into the base of the leaf segments, without a distinct joint. The axes are straight, rather than zig-zagging. [2] [5] Each blade has 4 to 6 pairs of pinnae, ovate or deltoid-ovate in shape. [6] These are in turn divided into 2 to 3 pairs [6] of orbicular (circular) [2] or deltoid to ovate pinnules, obtuse at the tip and cordate (heart-shaped) or truncate (abruptly terminating) at the base [6] and borne on a short stalk. [3] The ones closest to the blade base may be subdivided into another set of segments, while the pinnules closer to the blade tip are lobed or entire. [6] The leaf tissue is dark blue-green [3] and of a leathery to fleshy texture, [6] obscuring the veins from the upper surface, and does not bear hairs or scales on either surface. Unlike many species in the genus, farina (powder) is not present on either surface of the leaf. [2] [5] The leaves do not curl when dry. [3]

In fertile leaf segments, the sporangia are close to the margin, borne along the further half of the secondary veins branching from the midrib of the segment. Each sporangium contains 64 spores. The leaf segments, at most, are slightly curled under, not concealing the sporangia, and their tissue is not modified into a false indusium. [2] [5]

Argyrochosma jonesii leaflet, showing slightly curled leaf margins, exposed sporangia, and dark color entering base of leaf segments. Argyrochosma jonesii 6.jpg
Argyrochosma jonesii leaflet, showing slightly curled leaf margins, exposed sporangia, and dark color entering base of leaf segments.

A. jonesii is a sexual diploid, with a chromosome count of 2n = 54. [2] [5] A tetraploid cytotype was thought to exist, [5] but this is believed to be the result of plants occasionally producing 32 diploid (rather than 64 haploid) spores and giving rise to diploid gametophytes. [7]

It is most similar in appearance to the closely related A. lumholtzii , and both are present in Sonora, but the latter has a darker leaf stalk and axes and the leaf is less highly divided. [8]

Taxonomy

The species was first described in 1917 as Notholaena jonesii by William Ralph Maxon. It was named for Marcus E. Jones, who collected the material on which the description was based. [9]

Both Edwin Copeland and Charles Alfred Weatherby suggested in the 1940s that a group of ferns related to Notholaena nivea might represent a distinct genus of its own. [10] [11] Weatherby thought that, until that genus was described, the group might better be placed in Pellaea, rather than in Notholaena, but died in 1949 before he could circumscribe and publish it. Accordingly, in 1950, Conrad Vernon Morton transferred the species to Pellaea as P. jonesii, to provide a name for it in Thomas Henry Kearney's Flowering Plants and ferns of Arizona. [12] In 1958, Philip A. Munz, preparing a flora of California and following Copeland's opinion that Notholaena was best lumped into a broadly defined Cheilanthes , transferred it to that genus as C. jonesii. [13] John T. Mickel, carrying out a similar program of lumping in 1979, accidentally duplicated Munz's combination. [14]

The recognition of the N. nivea group as a genus was finally addressed in 1987 by Michael D. Windham, who was carrying out phylogenetic studies of the cheilanthoids. He elevated Notholaena sect. Argyrochosma to become the genus Argyrochosma , [15] and transferred this species to that genus as A. jonesii. [16] In 2018, Maarten J. M. Christenhusz transferred the species to Hemionitis as H. jonesii, as part of a program to consolidate the cheilanthoid ferns into that genus. [17]

Phylogenetic studies have shown that A. jonesii is a sister species to A. lumholtzii , a rare Sonoran species; these two species form a clade sister to another clade containing A. formosa and A. microphylla. [18] 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. [19]

Distribution and habitat

Argyrochosma jonesii is known in the United States from California, Arizona, Nevada, and southern Utah [20] and in Mexico from Sonora, [2] particularly within the Mojave and Sonoran Deserts. It grows on calcareous [5] or igneous [21] cliffs and ledges, at an altitude from 600 to 1,900 meters (2,000 to 6,200 ft). [5]

Conservation

Under the NatureServe conservation status system, A. jonesii is ranked as apparently secure (G4), but it is considered critically imperiled (S1) in Utah and imperiled (S2) in Nevada. [1]

Cultivation

It prefers high light, and moist-dry to dry, well-drained soil, perhaps of high pH. [22]

Notes and references

Related Research Articles

<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 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".

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 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 chipinquensis is a fern endemic to Mexico, a member of the family Pteridaceae. One of the cheilanthoid ferns, it was classified in the genus Cheilanthes until 2013, when the genus Myriopteris was again recognized as separate from Cheilanthes. It grows in oak-pine forests of the Sierra Madre Oriental, often with the very similar and closely related Myriopteris tomentosa.

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 NatureServe 2024.
  2. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Mickel & Smith 2004, p. 67.
  3. 1 2 3 4 5 6 7 8 9 10 11 Lellinger 1985, p. 153.
  4. 1 2 3 4 5 6 Tryon & Weatherby 1956, p. 83.
  5. 1 2 3 4 5 6 7 8 9 10 11 12 Windham 1993.
  6. 1 2 3 4 5 Tryon & Weatherby 1956, p. 84.
  7. ↑ Sigel et al. 2011, p. 560.
  8. ↑ Mickel & Smith 2004, pp. 67, 69.
  9. ↑ Maxon 1917, p. 108.
  10. ↑ Morton 1950, pp. 249–250.
  11. ↑ Windham 1987, p. 37.
  12. ↑ Morton 1950, pp. 249–251.
  13. ↑ Munz 1958, p. 87.
  14. ↑ Mickel 1979, p. 434.
  15. ↑ Windham 1987, p. 38.
  16. ↑ Windham 1987, p. 40.
  17. ↑ Christenhusz, Fay & Byng 2018, p. 16.
  18. ↑ Sigel et al. 2011, p. 558.
  19. ↑ Sigel et al. 2011, p. 559.
  20. ↑ Kartesz 2014.
  21. ↑ Lellinger 1985, p. 154.
  22. ↑ Hoshizaki & Moran 2001, p. 189.

Works cited

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