''Asplenium ruta-muraria'' is a species of

fern A fern (Polypodiopsida or Polypodiophyta ) is a member of a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. The polypodiophytes include all living pteridophytes except t ...

commonly known as wall-rue (but which, as a fern, is not by any means closely related to common

rue ''Ruta graveolens'', commonly known as rue, common rue or herb-of-grace, is a species of '' Ruta'' grown as an ornamental plant and herb. It is native to the Balkan Peninsula. It is grown throughout the world in gardens, especially for its bl ...

). It is a very small epipetric species, growing exclusively on

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

and other calcareous rocks. Its fronds are bluish-green and are heavily sub-divided, becoming up to 12 cm in length.

Taxonomy

Linnaeus first gave wall-rue the

binomial Binomial may refer to: In mathematics *Binomial (polynomial), a polynomial with two terms * Binomial coefficient, numbers appearing in the expansions of powers of binomials *Binomial QMF, a perfect-reconstruction orthogonal wavelet decomposition ...

''Asplenium ruta-muraria'' in his ''

Species Plantarum ' (Latin for "The Species of Plants") is a book by Carl Linnaeus, originally published in 1753, which lists every species of plant known at the time, classified into genera. It is the first work to consistently apply binomial names and was the ...

'' of 1753. A global

phylogeny A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological spec ...

of ''Asplenium'' published in 2020 divided the genus into eleven

clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...

s, which were given informal names pending further taxonomic study. ''A. ruta-muraria'' belongs to the "''Pleurosorus'' subclade" of the "''Pleurosorus'' clade". The ''Pleurosorus'' clade has a worldwide distribution; members are generally small and occur on hillsides, often sheltering among rocks in exposed habitats. ''A. ruta-muraria'' is exceptional within the subclade for its lack of hairs on the leaf. The phylogeny suggests that multiple

cryptic species In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...

may be present among plants now called ''A. ruta-muraria''. Within the subclade, the ''A. ruta-muraria'' aggregate (including ''A. dolomiticum'') is sister to the species formerly segregated in the genus ''Pleurosorus''.

Distribution and habitat

''Asplenium ruta-muraria'' is native to Europe, East Asia, and eastern North America. In North America, its range extends from western New England southwest along the

Appalachian Mountains The Appalachian Mountains, often called the Appalachians, (french: Appalaches), are a system of mountains in eastern to northeastern North America. The Appalachians first formed roughly 480 million years ago during the Ordovician Period. They ...

to Alabama and Tennessee. It is also found in the Ozarks and in southern Indiana and Ohio, with outlying occurrences in Michigan, Ontario, Quebec, and

Clinton County, Iowa Clinton County is a county located in the U.S. state of Iowa. As of the 2020 census, the population was 46,460. Its county seat is Clinton. Its name is in honor of the seventh Governor of New York State, DeWitt Clinton. Clinton County compris ...

. In

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

, it commonly invades masonry and is a common species, while in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

, it is more difficult to find, favouring pockets in very well-weathered and rather dry limestone outcrops.

Citations

References

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External links

* * {{Taxonbar, from=Q1125768 ruta-muraria Flora of England Flora of Lebanon Ferns of the United States Flora of Connecticut Ferns of Europe Plants described in 1753 Taxa named by Carl Linnaeus