Myriopteris lanosa

Leaf bases are closely spaced along the rhizome, which is generally 4 to 8 millimeters (0.2 to 0.3 in) in diameter[2] and rarely branched.[3] The rhizome bears persistent scales, which are linear to slightly lanceolate,[2] distantly toothed,[3] straight or slightly twisted, and loosely pressed against the surface of the rhizome. Most of them are brown in color, but at least a few will show a thin, dark central stripe, which does not stand out well from the rest of the scale color.[2]

The fronds spring up in clusters and emerge as fiddleheads (circinate vernation). When mature, they are 7 to 50 centimeters (2.8 to 19.7 in) long and 1.5 to 5 centimeters (0.59 to 1.97 in) wide.[2] Fertile and sterile fronds are similar in appearance.[4] The stipe (the stalk of the leaf, below the blade) is 3 to 18 centimeters (1.2 to 7.1 in) long.[3] It is dark brown[2] to purplish-black in color, with many long, persistent, dark-jointed hairs.[3][4] The upper surface is rounded.[2]

Closeup showing somewhat sparse, long, segmented hairs on Myriopteris lanosa leaves

The leaf blades range in shape from lanceolate to linear-oblong. The blade is usually bipinnate-pinnatifid (cut into pinnae and lobed pinnules) at the base.[2] Each blade is cut into 12 to 20 pairs of pinnae.[4] The rachis (leaf axis) is rounded on the upper side, dark in color, and bears soft hairs of uniform shape, but not scales. The pinnae are not jointed at the base, and the dark pigmentation of the rachis enters the edge of the pinnae.[2] The pinnae at the base of the leaf are slightly smaller than the pinnae immediately above them,[2][4] and the pinnae are more or less symmetric about the costa (pinna axis). The upper surfaces of the pinnae are sparsely covered with hairs. The upper sides of the costae are brown for most of their length and lack scales. The pinnules are lanceolate or oblong, and not bead-shaped as in some other species of Myriopteris.[2] There are 7 to 14 pairs of pinnules per pinna.[4] The largest pinnules are 3 to 5 millimeters (0.12 to 0.20 in) long, with a sparse covering of long, segmented hairs on both upper and lower surfaces.[2]

On fertile fronds, the sori are protected by false indusia formed by the edge of the leaf curling back over the underside. The false indusia look similar, though not identical, to the rest of the leaf tissue, and are 0.05–0.25 mm wide. Beneath them, the sori do not form long lines, but are discontinuous and concentrated on lobes at the tip and sides of the pinnule. Each sporangium in a sorus carries 64 spores. The diploid sporophyte has a chromosome number of 60.[2]

The common name "lip fern" comes from the position of the sporangia at the edge or lip of the leaf, typical of the genus,[5] while "hairy" refers to the presence of hairs, but not scales, on the stipe, in contrast with the similar Myriopteris tomentosa.[4]

The species was first described in 1803, based on material from Tennessee and North Carolina, by André Michaux, who named it Nephrodium lanosum.[6] The epithet lanosum means "woolly", referring to the texture of the hairs.[4][7] It was transferred by Jean Louis Marie Poiret to Polypodium as Polypodium lanosum in Lamarck's Encyclopédie Méthodique, Botanique in 1804.[8] In the same year, Kurt Sprengel independently described the species, based on material collected in the Carolinas by Louis Bosc, under the name of Adiantum vestitum.[9] The epithet vestitum, meaning "clothed",[10] presumably refers to the hairs covering the plant. In 1806, Olof Swartz transferred Michaux's species to Aspidium, a genus which he broadly circumscribed to include many ferns with scattered dot-like sori, as Aspidium lanosum.[11] He treated Sprengel's material as a different species, transferring it to the genus Cheilanthes as Cheilanthes vestita.[12]

Nicaise Auguste Desvaux, in 1811, recognized that the two species were the same, and placed them, based on the location of sori and the false indusia, in the genus Cincinalis under the name Cincinalis vestita (using the junior epithet).[13] In 1813, however, on the advice of Jussieu, he accepted Robert Brown's name of Notholaena as the correct one for the genus, and renamed the species Notholaena vestita.[14]

Early generic classifications, including those of Carl Borivoj Presl in 1836[15] and John Smith in 1842,[16] placed the species in a broadly circumscribed Cheilanthes. However, A.L.A. Fée's classification of 1852 recognized several segregates, including the new genus Myriopteris, which he separated from Cheilanthes proper by the presence of hairs among the sporangia and some characteristics of the indusium.[17] Fée did not examine Michaux's or Sprengel's species, but Smith recognized Myriopteris in his Cultivated Ferns of 1857 and transferred C. vestita into that genus.[18]

In 1859, Daniel Cady Eaton transferred Nephrodium lanosum to the genus Cheilanthes as Cheilanthes lanosa; he (erroneously) attributed material from the western United States to this taxon, which he distinguished from C. vestita from the eastern United States, as originally described.[19] When Eaton edited the ferns in the 5th Edition of Gray's Manual (1868), he continued to refer to eastern material as C. vestita.[20] Hooker & Baker, in their second edition of Synopsis Filicum (1874), followed the advice of Eaton in recognizing the eastern material as C. vestita and placing Michaux's specimens (notwithstanding their location) with western material in Cheilanthes lanuginosa. They did not recognize Myriopteris as a segregate genus.[21] In the same year, David Allan Poe Watt suggested that Sprengel's and Michaux's plants might be the same, and noted the priority of C. lanosa, while reviewing the nomenclature of North American Cheilanthes; that combination is sometimes attributed to him.[22]

In 1896, the Illustrated Flora of Britton and Brown recognized both taxa as synonymous, and adopted the name of C. lanosa for them.[23] The 7th edition of Gray's Manual, published in 1908 followed the same circumscription and name,[24] under which the species was generally known during the 20th Century. By a strict application of the principle of priority, Oliver Atkins Farwell transferred it to the genus Allosorus as Allosorus lanosus in 1920, that genus having been published before Cheilanthes.[25] Farwell's name was rendered unnecessary when Cheilanthes was conserved over Allosorus in the Paris Code published in 1956. M. L. Fernald reopened the question of the identity of Michaux's material in 1946, suggesting it had been mislabeled and really represented Cheilanthes tomentosa,[26] but this was refuted by C. V. Morton in 1967.[27]

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. lanosa, which thus became Myriopteris lanosa.[28] In 2018, Maarten J. M. Christenhusz transferred the species to Hemionitis as H. lanosa, as part of a program to consolidate the cheilanthoid ferns into that genus.[29]

Further molecular studies in Myriopteris demonstrated the existence of three well-supported clades within the genus. M. lanosa is nested in one of them, informally named the lanosa clade by Grusz et al., where the species forms the sister clade to Myriopteris longipila.[30] The lanosa clade is distinguished from all other species of the genus, except M. wrightii, by forming fiddleheads as leaves emerge.[31]

Myriopteris lanosa is found in the Appalachian Mountains from Connecticut southwest to Alabama, north through middle Tennessee into the Shawnee Hills and west through the Ozarks. Outlying populations can be found ranging to Wisconsin, the Oklahoma Panhandle, Louisiana, and west Florida.[32] One specimen was collected by Edgar T. Wherry in Harrison, McLennan County, Texas, in 1925; while it is believed to be authentic, there is little suitable habitat in the county and extensive sand and gravel quarrying have rendered its relocation unlikely.[33]

It grows in shallow soil[4] on rocky slopes and ledges,[2] although not usually on cliff faces,[34] at an altitude from 100 to 800 meters (300 to 3,000 ft).[2] It is not particularly sensitive to rock type, growing on limestone, granite and sandstone, among others.[2][34] It can also grow in open woodlands and other open areas.[4]

The species is globally secure, but is threatened in some states at the edge of its range. It has become extinct in Delaware, and is only known historically from New York. NatureServe considers it to be critically imperiled in Connecticut, Louisiana, and Texas, imperiled in Indiana, Kansas, Mississippi, and New Jersey, and vulnerable in Illinois.[1]

This fern is easily cultivated, and should be grown under medium-high light in well-drained, acidic soil. The soil should be dry to slightly moist.[34]