Myriopteris rawsonii

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Myriopteris rawsonii
Myriopteris rawsonii habit.jpg
Myriopteris rawsonii growing in a crevice among rocks
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Plantae
Clade: Tracheophytes
Division: Polypodiophyta
Class: Polypodiopsida
Order: Polypodiales
Family: Pteridaceae
Genus: Myriopteris
Species:
M. rawsonii
Binomial name
Myriopteris rawsonii
(Pappe) Grusz & Windham
Synonyms
  • Cheilanthes rawsonii(Pappe) Mett. ex Kuhn
  • Hemionitis rawsonii(Pappe) Christenh.
  • Notholaena rawsoniiPappe

Myriopteris rawsonii, formerly known as Cheilanthes rawsonii, [1] is a perennial fern native to Namaqualand in Southern Africa. Like many other cheilanthoid ferns, it is adapted to dry conditions, bearing a thick layer of pale hairs on the underside of its pinnate-pinnatifid leaves. It is the only African representative of its clade of cheilanthoids, the otherwise American genus Myriopteris . It spends much of the year in a dried-out, dormant state, rehydrating and putting out new growth during winter rains. Its name honors the botanist and civil servant Sir Rawson W. Rawson.

Contents

Description

The fronds arise from a creeping rhizome about 2.5 millimeters (0.098 in) in diameter. The rhizome bears linear scales up to 2 millimeters (0.08 in) long, which are blackish-brown in color, growing pale brown at the margins. The scales are jagged at the edges, or ciliate (bearing hair-like projections). [2]

The fronds are closely spaced along the rhizome, standing erect or arching somewhat. [2] They emerge as fiddleheads (circinate vernation). [3] The stipe (the stalk of the leaf, below the blade) is about 50 millimeters (2 in) long. It is brown and covered with a mat of pale hairs in freshly-grown leaves; the hairs are shed as the leaf ages. [2]

The leaf blade is linear-elliptic in shape and pinnate-pinnatifid (cut into deeply lobed pinnae), sometimes almost bipinnate. The blades range from 80 to 250 millimeters (3.1 to 9.8 in) long and from 15 to 22 millimeters (0.59 to 0.87 in) wide. The rachis (leaf axis) is similar in appearance to the stipe, but largely retains its hairs even in older fronds. The pinnae (leaflets) are oblong-ovate in shape and relatively widely spaced from each other, with entire (untoothed) margins. Those closer to the base of the leaf are more deeply lobed than those above. The veins are not netted and do not stand out strongly from the rest of the leaf tissue. The lower surface of the leaf is covered in a thick mat of pale reddish hairs, while the upper surface has few or none. [2]

The sori occur at the margins of the pinnae. They are round and do not fuse with each other, and are not protected by an indusium. [2]

M. rawsonii is fairly distinctive in appearance from other ferns of Southern Africa. Cheilanthes contracta , which occurs just to the south around the Cape of Good Hope, is somewhat similar, but is a bit more dissected (bipinnate to bipinnate-pinnatifid), has a shorter stipe (about 10 millimeters (0.4 in)), more hair on the upper surface of the leaf, and pinnae rotated out of the plane of the leaf axis to some extent. [2]

Taxonomy

The species was first described in 1858 by the South African botanist Karl Wilhelm Ludwig Pappe in Synopsis filicum Africae Australis, a South African fern flora. Pappe named it Notholaena rawsonii, basing the description on material collected in Namaqualand in 1856 by Rev. Henry Whitehead. [4] The name honors Pappe's coauthor Rawson W. Rawson. [2] Pappe and Rawson distinguished the genera Notholaena and Cheilanthes in part on whether the sori were continuous or solitary. [5] Other contemporary pteridologists did not recognize this distinction. Friedrich Adalbert Maximilian Kuhn, in his Filices Africae of 1868, followed the unpublished notes of the recently deceased Georg Heinrich Mettenius in choosing to transfer it to Cheilanthes as C. rawsonii, [6] the name that would typically be used for it during the 20th century.

The development of molecular phylogenetic methods showed that the traditional circumscription of Cheilanthes is polyphyletic. Convergent evolution in arid environments is thought to be responsible for widespread homoplasy in the morphological characters traditionally used to classify it and the segregate genera that have sometimes been recognized. On the basis of molecular evidence, Amanda Grusz and Michael D. Windham revived the genus Myriopteris in 2013 for a group of species formerly placed in Cheilanthes. One of these was C. rawsonii, which they transferred to that genus as M. rawsonii. It is the only member of the genus native to Africa; all other species are American. [1] In 2018, Maarten J. M. Christenhusz transferred the species to Hemionitis as H. rawsonii as part of a program to consolidate the cheilanthoid ferns into that genus. [7]

Further molecular studies in Myriopteris demonstrated the existence of three well-supported clades within the genus. M. rawsonii belongs to what Grusz et al. informally named the lanosa clade, where it is sister to the Sonoran Desert endemic M. parryi . [8] The lanosa clade is distinguished from all other species of the genus, except M. wrightii , by forming fiddleheads as leaves emerge. [3]

Distribution and habitat

Myriopteris rawsonii occurs only in Namaqualand, ranging from southern Namibia into the northern part of the Northern Cape province of South Africa. [2]

It is found on hot, rocky hillsides, often on south- or east- facing slopes where crevices or boulders offer some shade and help preserve moisture for the plant. It occurs at elevations of 400 to 1,660 meters (1,310 to 5,450 ft). [2]

Ecology and conservation

The fronds typically remain dormant most of the year, shriveled and curled around their central axis. They rehydrate, unfurl, and new growth appears when refreshed by winter rains. [2]

Notes and references

Related Research Articles

<i>Myriopteris covillei</i> Species of fern in family Pteridaceae

Myriopteris covillei, formerly known as Cheilanthes covillei, is a species of cheilanthoid fern known by the common name Coville's lip fern. Coville's lip fern is native to the southwestern United States and Mexico.

<i>Myriopteris clevelandii</i> Species of fern in family Pteridaceae

Myriopteris clevelandii, formerly known as Cheilanthes clevelandii, is a species of lip fern known by the common name Cleveland's lip fern. It is native to southern California and Baja California in Mexico. The leaf is divided into small, bead-like segments densely covered with scales beneath. In M. clevelandii, some of these scales are reduced to hairlike structures, which help distinguish it from the closely related M. covillei. It is usually found growing on exposed rock, particularly igneous rock.

<i>Myriopteris cooperae</i> Species of fern in family Pteridaceae

Myriopteris cooperae, formerly Cheilanthes cooperae, is a species of lip fern known by the common name Mrs. Cooper's lip fern, or simply Cooper's lip fern. Its leaves grow in clusters and are highly dissected into oblong segments, rather than the beadlike segments found in some other members of the genus. The axes of the leaves are dark and covered in long, flattened hairs. It is endemic to California, where it grows in rocky habitats, usually over limestone. The species was named in honor of its collector, Sarah Paxson Cooper; according to Daniel Cady Eaton, who described it in 1875, it was the first fern species to be named for a female botanist.

<i>Myriopteris tomentosa</i> Species of fern in family Pteridaceae

Myriopteris tomentosa, formerly known as Cheilanthes tomentosa, is a perennial fern known as woolly lipfern. Woolly lipfern is native to the southern United States, from Virginia to Arizona and Georgia, and Mexico.

<i>Myriopteris lanosa</i> Species of fern

Myriopteris lanosa, the hairy lip fern, is a moderately-sized fern of the eastern United States, a member of the family Pteridaceae. Its leaves and stem are sparsely covered in hairs, but lack scales, hence its common name. One of the cheilanthoid ferns, it was usually classified in the genus Cheilanthes until 2013, when the genus Myriopteris was again recognized as separate from Cheilanthes. It typically grows in shallow, dry, soil, often in rocky habitats.

<i>Myriopteris</i> Genus of ferns

Myriopteris, commonly known as the lip ferns, is a genus of cheilanthoid ferns. Like other cheilanthoids, they are ferns of dry habitats, reproducing both sexually and apogamously. Many species have leaves divided into a large number of small, bead-like segments, the probable inspiration for the generic name. Hairs and/or scales are often present on both the upper and lower surfaces of the leaf, and their presence and appearance are useful in distinguishing between species. The genus is most diverse in Mexico, but species are found from southwestern Canada south to southern Chile, and one species is endemic to southern Africa.

<i>Myriopteris alabamensis</i> Species of fern in family Pteridaceae

Myriopteris alabamensis, the Alabama lip fern, is a moderately-sized fern of the United States 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 alabamensis until 2013, when the genus Myriopteris was again recognized as separate from Cheilanthes. It typically grows in shade on limestone outcrops.

Myriopteris maxoniana is a species of cheilanthoid fern endemic to the Mexican state of Tamaulipas. It is known only from one collection. It closely resembles Myriopteris longipila and was not described as a distinct taxon until 2004.

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.

Myriopteris yatskievychiana is a small fern endemic to the Mexican state of Sonora, a member of the family Pteridaceae. It is known only from a single collection. While superficially similar to golden lip fern, a widespread species in Mexico, differences in its coating of hairs and its small size make it distinctive. One of the cheilanthoid ferns, it was usually classified in the genus Cheilanthes until 2013, when the genus Myriopteris was again recognized as separate from Cheilanthes.

Myriopteris allosuroides is a moderately-sized fern endemic to Mexico, a member of the family Pteridaceae. Unlike many members of its genus, its rachides are grooved on the upper surface and largely free of hairs or scales. One of the cheilanthoid ferns, it was usually classified in the genera Cheilanthes or Pellaea until 2013, when the genus Myriopteris was again recognized as separate from Cheilanthes. It typically grows on dry, rocky slopes over acidic, particularly basaltic, 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.

<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.

<i>Myriopteris aurea</i> Species of fern in family Pteridaceae

Myriopteris aurea, the golden lip fern or Bonaire lip fern, is a moderately-sized fern native to the Americas, a member of the family Pteridaceae. Unlike many members of its genus, its leaf is only modestly dissected into lobed leaflets (pinnae), which are hairy both above and below. One of the cheilanthoid ferns, until 2013 it was classified in the genus Cheilanthes as Cheilanthes bonariensis, when the genus Myriopteris was again recognized as separate from Cheilanthes. It typically grows on dry, rocky slopes, and ranges from Mexico, where it is common and widespread, and the southwestern United States south and east through Central and South America as far as Chile and Argentina.

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>Myriopteris rufa</i> Species of fern in family Pteridaceae

Myriopteris rufa, commonly known as Eaton's lip fern, is a moderately-sized fern of Mexico and the southwestern United States, with outlying populations in Costa Rica and the Appalachian Mountains. One of the cheilanthoid ferns, it was usually classified in the genus Cheilanthes, as Cheilanthes eatonii, until 2013, when the genus Myriopteris was again recognized as separate from Cheilanthes. It typically grows in rocky habitats, most frequently on limestone but also sometimes on basalt or shale.

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.

Myriopteris mickelii is a fern endemic to southern Mexico. It is very similar to M. cinnamomea of Central America, from which it was separated when described in 1980, and to other species in the "alabamensis clade" of Myriopteris. Named after the pteridologist John T. Mickel, it grows on dry, lightly shaded slopes and banks.

References

  1. 1 2 Grusz & Windham 2013.
  2. 1 2 3 4 5 6 7 8 9 10 Crouch et al. 2011, p. 350.
  3. 1 2 Grusz et al. 2014, pp. 705.
  4. ↑ Pappe & Rawson 1858, p. 42.
  5. ↑ Pappe & Rawson 1858, pp. 5, 10.
  6. ↑ Kuhn 1868, p. 75.
  7. ↑ Christenhusz, Fay & Byng 2018, p. 20.
  8. ↑ Grusz et al. 2014, pp. 703.

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.
  • Crouch, Neil R; Klopper, Ronell R; Burrows, John E; Burrows, Sandra M (2011). Ferns of Southern Africa. Cape Town, South Africa: Struik Nature. ISBN   978-1-77007-910-6.
  • Grusz, Amanda L.; Windham, Michael D. (2013). "Toward a monophyletic Cheilanthes: The resurrection and recircumscription of Myriopteris (Pteridaceae)". PhytoKeys (32): 49–64. doi: 10.3897/phytokeys.32.6733 . PMC   3881352 . PMID   24399906.
  • Grusz, Amanda L.; Windham, Michael D.; Yatskievych, George; Huiet, Lane; Gastony, Gerald J.; Pryer, Kathleen M. (2014). "Patterns of Diversification in the Xeric-adapted Fern Genus Myriopteris (Pteridaceae)". Systematic Botany. 39 (3): 698–714. doi:10.1600/036364414X681518. JSTOR   24546228.
  • Kuhn, Maximilian (1868). Filices Africae. Leipzig: W. Engelmann. p. 75.
  • Pappe, L.; Rawson, Rawson W. (1858). Synopsis filicum Africae Australis. Cape Town, South Africa: Saul Solomon and Co.


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