Phyllitis japonica subsp. americana (Fernald) Á. Löve & D. Löve
Phyllitis lindenii (Hook.) Maxon
Phyllitis scolopendrium (L.) Newman
Phyllitis scolopendrium var. americana Fernald
Phyllitis scolopendrium var. scolopendrium (L.) Newman
Scolopendrium lindenii Hook.
Scolopendrium officinarum Sw.
Scolopendrium scolopendrium (L.) H. Karst.
Scolopendrium vulgare Sw.
Asplenium scolopendrium, commonly known as the hart's-tongue fern,[3] is an
evergreenfern in the
familyAspleniaceae native to the Northern Hemisphere.
Description
The most striking and unusual feature of the fern is its simple, strap-shaped undivided
fronds. The leaves' supposed resemblance to the tongue of a
hart (an archaic term for a male
red deer) gave rise to the common name "hart's-tongue fern".
Taxonomy
Linnaeus first gave the hart's-tongue fern the
binomialAsplenium scolopendrium in his Species Plantarum of 1753.[4] The Latin
specific epithetscolopendrium is derived from the Greek skolopendra, meaning a centipede or millipede; this is due to the
sori pattern being reminiscent of a
myriapod's legs.[5][6]
A global phylogeny of Asplenium published in 2020 divided the genus into eleven clades,[7] which were given informal names pending further taxonomic study. A. scolopendrium belongs to the "Phyllitis subclade" of the "Phyllitis clade".[8] Members of the Phyllitis clade have undivided or pinnatifid leaf blades with a thick, leathery texture, persistent scales on their stalk, and often possess
anastomosing veins. Members of the Phyllitis subclade have undivided leaves with freely branching veins and single or paired sori. They are widely distributed through the Northern Hemisphere.[9] If defined to inclued the former A. komarovii, A. scolopendrium makes up the former segregate genus Phyllitis and is sister to A. sagittatum.[8]
Three subspecies were accepted in the most recent revision of the species:[10]
A. scolopendrium subsp. scolopendrium is native to
Europe,
North Africa, the
Middle East, and
Central Asia. Populations in the eastern Mediterranean have been referred to as A. scolopendrium var. antri-jovis.
A. scolopendrium subsp. americanum is native to
Ontario in
Canada, the
United States, southern
Mexico, and
Hispaniola. The tropical populations have been referred to as A. scolopendrium var. lindenii.
A. scolopendrium subsp. japonicum, formerly A. komarovii, is native to eastern
Russia,
China,
Taiwan, and
Japan
Morphological differences between the varieties are minor, but the North American variety americanum is
tetraploid, while the
Old World subspecies A. scolopendrium scolopendrium) is
diploid.[11]
Distribution
Asplenium scolopendrium is a common species in the Old World:
The subspecies scolopendrium occurs throughout
Europe (including the
Caucasus and the
British Isles), the
Middle East, and North Africa (in
Morocco,
Algeria,
Tunisia and
Libya, as well as the
Canary Islands). It has also been introduced to the
Falkland Islands. A. scolopendrium var. scolopendrium is rarely found in North America. Unlike its American counterpart, the scolopendrium of Europe is used for many horticultural uses. [12][13] Specimens of this variety found in North America (such as in
New Brunswick and
Ontario in Canada, and
Maryland in the United States) are considered naturalized descendants of cultivated plants.[14]
In
North America, it occurs in rare, widely scattered populations located in different locales:
In 2020, a new population of hart's-tongue ferns was discovered inside a cave with basaltic lava flows in
El Malpais National Monument,
Cibola County, New Mexico; this represents the first confirmed population of the species in North America west of the Mississippi. Genetic analyses and surveys are currently being performed to determine the population's variation and overall health. [19]
The unique dispersal of Asplenium scolopendrium has caught the attention of international botanists. In fact, the very existence of such varieties beg that "...these populations arose following colonization events involving a single spore".[20]
Habitat
The plants grow on neutral, calcium-rich, and/or lime-rich substrates under deciduous hardwood canopies (usually
sugar maples in eastern North America), including moist soil and damp crevices in old walls; they are found most commonly in shaded areas. Plants in full sun are usually stunted and yellowish in colour, while those in full shade are dark green and healthy. The disjunct populations of the North American variation in the southeastern US are found exclusively in sinkhole pits or limestone caves.[21] These populations may be relics of cooler
Pleistocene climates.[17]
Conservation
United States
In the United States, A. scolopendrium var. americanum was declared endangered by the
U.S. Fish and Wildlife Service in 1989.[21] The reasons for its rarity are currently being researched, with
reintroduction programs in New York and elsewhere also in development.[22]
Canada
Ontario, Canada has the highest population numbers of A. scolopendrium var. americanum of any region in the variation's distribution, with around 80% of all subpopulations and around 94% of all individuals. The fern was reported at more than 100 sites across the province, with around 75 still believed to be existing. Despite this, A. scolopendrium var. americanum was listed as a species of
Special Concern under the Committee on the Status of Species at Risk in Ontario in May 2017, due to its extremely specific habitat requirements, relatively small distribution, and some subpopulations consisting of too little individuals.[23][24]
Europe
In spite of being much more common in Europe than in North America (and therefore present in more protected areas), A. scolopendrium is still declining in certain areas of the continent. The fern was listed as "Vulnerable" in the National Red Lists for
Albania in 2014[25] and
Norway in 2010 (under Criterion D1);[26] considered "critically threatened and rare" in the
Czech Republic's 2012 plant Red List;[27] and "Endangered" in
Sweden's 2010 Red List.[28] However, it was not considered threatened in
Germany's 1996 Red List of Threatened Plants.[29]A. scolopendrium is protected by law in the
Netherlands since 1998.[30]
The American variety is reputed to be difficult to cultivate (making conservation efforts for it even more troublesome); due to this, most, if not all, cultivated individuals are derived from the Old World subspecies.[33]
Herbal medicine
This fern was used in the 1800s as a
medicinal plant in folk medicine as a
spleen tonic (hence an archaic name for the genus, "spleenworts") and for other uses.[34]
^Pence, V. C. (2015, July). Propagation and cryopreservation of Asplenium scolopendrium var ... - JSTOR. American Fern Journal. Retrieved March 17, 2023, from
https://www.jstor.org/stable/44076071
^Kartesz, J.T. 1999. A synonymized checklist and atlas with biological attributes for the vascular flora of the United States, Canada, and Greenland. First edition. In: Kartesz, J.T., and C.A. Meacham. Synthesis of the North American Flora, Version 1.0. North Carolina Botanical Garden, Chapel Hill, N.C.
^
abCurrie, Robert R. (September 1993).
American hart's-tongue recovery plan(PDF) (Report). Atlanta, Georgia: U.S. Fish and Wildlife Service. Retrieved 2010-02-28.
^Kålås, J.A., Viken, Å. and Bakken, T. (eds). 2006. Norsk Rødliste 2006 – 2006 Norwegian Red List. Artsdatabanken.
^Grulich, V. 2012. Red List of vascular plants of the Czech Republic: 3rd edition. Preslia 84: 631-645.
^Gärdenfors, U. 2010. Rödlistade arter i Sverige - The 2010 Red List of Swedish Species. ArtDatabanken, SLU, Uppsala.
^Ludwig, G. and Schnittler, M. 1996. Red List of Threatened Plants in Germany (Rote Liste gefährdeter Pflanzen Deutschlands). Bundesamt für Naturschutz, Bonn.
Hyde, H. A., Wade, A. E., & Harrison, S. G. (1978). Welsh Ferns. National Museum of Wales.
ISBN0-7200-0210-9.
Parker, Rosemarie (December 2009).
"A Real Rarity". Finger Lakes Native Plant Society. A popular article on hart's tongue fern that includes several references and a discussion of cultivation possibilities for the European and American varieties. The article strongly discourages collection and or cultivation of the North American variety.