{{short description|Genus of ferns in the family Pteridaceae}} {{automatic taxobox | image = Argyrochosma jonesii 3.jpg | image_caption = ''Argyrochosma jonesii'' | taxon = Argyrochosma | authority = (J.Sm.) Windham | subdivision_ranks = Species | subdivision = See text. | type_species = ''Pteris nivea'' | type_species_authority = Poir. }}
'''''Argyrochosma''''' is a genus of ferns known commonly as '''false cloak ferns'''. The genus is included in the Cheilanthoideae subfamily of the Pteridaceae.<ref name=Christenhusz-2011/> 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.
==Description== The fronds of ''Argyrochosma'' species are generally shorter than {{convert|40|cm|abbr=on}} 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.
==Taxonomy== The group of species comprising the genus was first described by John Smith in 1842 as ''Notholaena'' sect. ''Argyrochosma''. He included in the genus species with a variety of coverings on the undersurface of the leaf, and assigned to this section those that were covered in white farina.{{sfn|Smith|1842|p=50}} Smith's name is derived from the Greek words ἄργυρος (''argyros''), "silver" and χῶσμα (''chosma''), "mound of earth".{{sfn|Quattrocchi|2000|p=193}}{{efn|Sometimes freely translated as "powder",{{sfn|Windham|1993}} although Smith's original division of ''Notholaena'' into sections ''Argyrochosma'', ''Eriochosma'' and ''Lepichosma'' depending on whether white farina, tomentose hairs, or scales covered the underside{{sfn|Smith|1842|p=50}} suggests an emphasis on the heaping of material.}} Carl Christensen considered the section to be more properly classified in ''Pellaea'', and designated ''Pellaea nivea'' as the lectotype for it.{{sfn|Christensen|1906|p=XL}}
By the late 20th century, most authorities favored placement of a group of ferns, exemplified by ''Notholaena nivea'', either in ''Notholaena'' or ''Pellaea''. Both Edwin Copeland and C. A. Weatherby suggested in the 1940s that the group might represent a distinct genus of its own.{{sfn|Windham|1987|p=37}} In 1948, Weatherby advised Conrad Vernon Morton, preparing some treatments of American ferns, that these species, including some similar to ''N. nivea'' but without farina, were better placed as a section of ''Pellaea'' than in ''Notholaena''. In the following year, he advised Morton that "this is one of the two groups (and the better of the two) which I can see clearly as a segregate genus...which...should bear the name ''Argyrochosma'' (J. Smith). I may live to publish on this."{{sfn|Morton|1950|pp=249–250}} He did not, and so the task was 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''''' and made suitable combinations for the recognized species.{{sfn|Windham|1987|p=38}} Two varieties of ''Argyrochosma nivea'' were transferred to the new genus in 1996 by M. Mónica Ponce,{{sfn|Ponce|1996|p=177}} and subsequently elevated to species level in the genus in 2017 by Michael Kessler and Alan R. Smith.{{sfn|Kessler|Smith|Prado|2017|p=206}} Meanwhile, in 2015, Gangmin Zhang and co-workers identified ''Argyrochosma connectens'', a rare Chinese species formerly placed in ''Pellaea'', as a member of the genus by DNA analysis.{{sfn|Wang|Yang|Mao|Zhao|2015|p=37}}
Members of the genus ''Argyrochosma'' are commonly known as '''false cloak ferns''' or '''silver ferns'''.{{sfn|Diggs|Lipscomb|2014|p=213}} "False cloak fern" refers to the historical placement of these species in the genus ''Notholaena''. The name of that genus is derived from Greek, meaning "false cloak", referring to the fact that the sori are not covered by well-differentiated tissue of the leaf margin, and its species were commonly known as "cloak ferns".{{sfn|Clute|1901|pp=287}} "Silver fern" is evidently derived from the name ''Argyrochosma'', which means "silver mound" and refers to the white farina found on the underside of the leaves of most species.{{sfn|Quattrocchi|2000|p=193}}
==Species== {{As of|2025|July}}, the ''Checklist of Ferns and Lycophytes of the World'' recognized the following nineteen species:<ref name=CFLW/> *''Argyrochosma chilensis'' <small>(Fée ex J.Rémy) Windham</small> *''Argyrochosma connectens'' <small>(C.Chr.) G.M.Zhang</small> *''Argyrochosma dealbata'' <small>(Pursh) Windham</small> - powdery false cloak fern *''Argyrochosma delicatula'' <small>(Maxon & Weath.) Windham</small> *''Argyrochosma fendleri'' <small>(Kunze) Windham</small> - Fendler's false cloak fern *''Argyrochosma flavens'' <small>(Sw.) M.Kessler & A.R.Sm.</small> *''Argyrochosma formosa'' <small>(Liebm.) Windham</small> *''Argyrochosma incana'' <small>(C.Presl) Windham</small> - hairy false cloak fern *''Argyrochosma jonesii'' <small>(Maxon) Windham</small> - Jones' false cloak fern *''Argyrochosma limitanea'' <small>(Maxon) Windham</small> - southwestern false cloak fern *''Argyrochosma lumholtzii'' <small>(Maxon & Weath.) Windham</small> *''Argyrochosma microphylla'' <small>(Mett. ex Kuhn) Windham</small> - small-leaf false cloak fern *''Argyrochosma nivea'' <small>(Poir.) Windham</small> *''Argyrochosma pallens'' <small>(Weath. ex R.M.Tryon) Windham</small> *''Argyrochosma palmeri'' <small>(Baker) Windham</small> *''Argyrochosma peninsularis'' <small>(Maxon & Weath.) Windham</small> *''Argyrochosma pilifera'' <small>(R.M.Tryon) Windham</small> *''Argyrochosma stuebeliana'' <small>(Hieron.) Windham</small> *''Argyrochosma tenera'' <small>(Gillies ex Hook.) M.Kessler & A.R.Sm.</small>
==Distribution and habitat== These ferns are mostly native to the Americas, from North to South and including the Caribbean, while one species, ''A. connectens'', is known from Sichuan, China.{{sfn|Wang|Yang|Mao|Zhao|2015|p=30}} They are commonly found growing in crevices of rocks.
==Notes== {{notelist}}
==References== {{Reflist|refs= <ref name=CFLW>{{cite WF |taxon=Argyrochosma |access-date=2025-07-15}}</ref>
<ref name=Christenhusz-2011>{{cite journal | first1=Maarten J. M. | last1=Christenhusz | first2=Xian-Chun | last2=Zhang | first3=Harald | last3=Schneider | title=A linear sequence of extant families and genera of lycophytes and ferns | journal=Phytotaxa | volume=19 | pages=7–54 | date=18 February 2011 | issue=1 | doi=10.11646/phytotaxa.19.1.2 | bibcode=2011Phytx..19....7C | url=http://www.mapress.com/phytotaxa/content/2011/f/pt00019p054.pdf | issn=1179-3163}}</ref> }}
==Sources== {{sfn whitelist|CITEREFWindham1993}} *{{cite book |last=Christensen |first=Carl |author-link=Carl Christensen (botanist) |title=Index Filicum |volume=Fascicles 1-12 |year=1906 |publisher=H. Hagerup |location=Copenhagen |url=https://www.biodiversitylibrary.org/page/3524058}} *{{cite book | title=Our Ferns in Their Haunts | url=https://archive.org/details/cu31924089416774 | first=Willard N. | last=Clute | author-link=Willard Nelson Clute | publisher=Frederick A. Stokes Co. | location=New York | year=1901}} *{{cite book |title=The Ferns and Lycophytes of Texas |last1=Diggs |first1=George M. Jr. |last2=Lipscomb |first2=Barney L. |publisher=Botanical Research Institute of Texas Press |location=Fort Worth, Texas |year=2014 |isbn=978-1-889878-37-9}} *{{cite journal |last1=Kessler |first1=Michael |last2=Smith |first2=Alan R. |last3=Prado |first3=Jefferson |title=Prodromus of a fern flora for Bolivia. XXVII. Pteridaceae |year=2017 |journal=Phytotaxa |volume=332 |issue=3 |pages=201–250 |doi=10.11646/phytotaxa.332.3.1 |url=https://www.researchgate.net/publication/322009872}} *{{cite journal |last=Ponce |first=M. Mónica |title=Nuevas combinaciones en Argyrochosma (Pteridaceae) |language=es |journal=Hickenia |volume=2 |issue=38 |year=1996 |pages=177–178 |url=https://www.hickenia.darwin.edu.ar/index.php/hickenia/article/view/191}} *{{cite journal |last=Morton |first=C. V. |author-link=Conrad Vernon Morton |title=Notes on the ferns of the eastern United States (concluded) |year=1950 |journal=American Fern Journal |volume=40 |issue=4 |pages=241–252 |doi=10.2307/1545864 |jstor=1545864 |url=https://www.biodiversitylibrary.org/page/32415554}} *{{cite book |last=Quattrocchi |first=Umberto |title=CRC World Dictionary of Plant Names |year=2000 |volume=I |publisher=CRC Press |location=Boca Raton, Florida |isbn=0-8493-2675-3}} *{{cite journal |year=1842 |title=An arrangement and definition of the genera of ferns |last=Smith |first=John |author-link=John Smith (botanist) |journal=Journal of Botany |volume=4 |pages=38–70 |url=https://www.biodiversitylibrary.org/page/2911834}} *{{cite journal | first=Michael D. |last=Windham |author-link=Michael D. Windham |title=Argyrochosma, a new genus of cheilanthoid ferns |journal=American Fern Journal |volume=77 |issue=2 |pages=37–41 |year=1987 |url=https://www.biodiversitylibrary.org/page/32225981 |doi=10.2307/1547438 |jstor=1547438 }} *{{efloras|1|102560|Argyrochosma|volume=2 | last=Windham |first=Michael D. |author-link=Michael D. Windham}} *{{cite journal |first1=Wan |last1=Wang |first2=Wenli |last2=Yang |first3=Xingxing |last3=Mao |first4=Ranran |last4=Zhao |first5=Ping |last5=Dou |first6=Gangmin |last6=Zhang |title=The phylogenetic affinities of Pellaea connectens, a rare endemic Chinese fern |journal=Phytotaxa |volume=220 |issue=1 |pages=30–42 | year=2015 |url=https://www.biotaxa.org/Phytotaxa/article/view/phytotaxa.220.1.2 |doi=10.11646/phytotaxa.220.1.2 |url-access=subscription }}
==Further reading== *{{cite journal |last1=Sigel |first1=Erin M. |last2=Windham |first2=Michael D. |author-link2=Michael D. Windham |last3=Huiet |first3=Layne |last4=Yatskievych |first4=George |last5=Pryer |first5=Kathleen M. |author-link5=Kathleen M. Pryer |title=Species Relationships and Farina Evolution in the Cheilanthoid Fern Genus Argyrochosma (Pteridaceae) |journal=Systematic Botany |volume=36 |issue=3 |year=2011 |pages=554–564 |doi=10.1600/036364411X583547 |jstor=23028975|bibcode=2011SysBo..36..554S |s2cid=16214744 }}
==External links== {{Wikispecies}} {{commons category|Argyrochosma}} *[http://ucjeps.berkeley.edu/cgi-bin/get_JM_treatment.pl?92,97 Jepson Manual Treatment] *[https://plants.usda.gov/java/profile?symbol=ARGYR5 USDA Plants Profile]
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Category:Argyrochosma Category:Fern genera Category:Ferns of the Americas Category:Ferns of China