Biology
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Like all ferns, the oblong woodsia reproduces by producing spores instead of seeds. These spores develop a small green disc called a prothallus, which in turn produces the gametes. The gametes have to swim through water to reach each other in order to fuse and produce a new spore-bearing plant. The thinnest of films will do, but this reliance on water means the fern is limited to a habitat that remains wet or moist for at least part of the year.
Conservation
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The oblong woodsia is listed in the UK Biodiversity Action Plans, and included in English Nature's Species Recovery Programme and Scottish Natural Heritage's Species Action Programme. All known populations are protected within Sites of Special Scientific Interest (SSSIs) and three are with National Nature Reserves (NNRs).
Attempts have begun to re-establish ex-situ populations. The Royal Botanic Gardens, Edinburgh, have grown sporelings collected under license from most of the wild sites in 1996. Plants have been reintroduced in Teesdale in the north of England, and in the southern uplands of Scotland, and these are being monitored each year to check the progress of the species recovery.
Description
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This fern, thought to be Britain's rarest, is small in comparison with other members of its class. The variable-length leaves are a mid-green and their undersides are very hairy. The reddish-brown stalks are also hairy and covered in scales.
Habitat
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This is a plant of tree-less, rocky habitats above 350 m, found growing in crevices in rock or on ledges in Britain, but in Europe it is found in woodland and even coastal areas.
Range
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Oblong woodsia is common in Sweden and Norway and scattered across central Europe and Iceland. In the UK it is limited to five 10 km squares, with the largest colony in the Lake District and other populations in Scotland and Wales.
Status
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Classified as Endangered in the UK.
Threats
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Like the Killarney fern, oblong woodsia was a victim of the Victorian craze for collecting. It used to be thought that over-collecting was responsible for the plant's seeming inability to reproduce readily in the wild through a reduction in genetic viability. This is now believed to be untrue. The species is on the edge of its range in the UK and it is thought that the greatest threat to its survival here is climate change. With such isolated populations, there is little chance of the fern migrating to new sites should temperatures rise.
Comments
provided by eFloras
Although generally separable by the characters given in the key, shade forms of Woodsia ilvensis with a reduced number of scales and hairs are occasionally misidentified as W . alpina . The morphologic distinctions between these species are further blurred by natural hybridization, which produces the intermediate triploid known as W . × gracilis . Some of the best characters for distinguishing these taxa are spore size and morphology. Spores average less than 46 µm in W . ilvensis , more than 46 µm in W . alpina , and are malformed and abortive in W . × gracilis . Woodsia ilvensis also hybridizes with W . oregana subsp. cathcartiana to form the sterile triploid W . × abbeae (F. S. Wagner 1987).
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Description
provided by eFloras
Stems compact, erect to ascending, with abundant persistent petiole bases of ± equal length; scales uniformly brown, lanceolate. Leaves 4.5--25 × 1.2--3.5 cm. Petiole usually brown or dark purple when mature, articulate above base at swollen node, relatively brittle and easily shattered. Blade narrowly lanceolate, usually 2-pinnate proximally, lacking glands, never viscid; rachis usually with abundant hairs and scales. Pinnae ovate-lanceolate to deltate, longer than wide, abruptly tapered to a rounded or broadly acute apex; largest pinnae with 4--9 pairs of pinnules; abaxial surface with mixture of hairs and linear-lanceolate scales, adaxial surface with multicellular hairs concentrated along midrib. Pinnules entire or crenate, rarely shallowly lobed; margins nonlustrous, thin, ciliate with multicellular hairs, lacking translucent projections. Vein tips frequently enlarged to form whitish hydathodes visible adaxially. Indusia of narrow, hairlike segments, these uniseriate throughout, composed of cells many times longer than wide, usually surpassing mature sporangia. Spores averaging 39--46 µm. 2 n = 82.
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Distribution
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Greenland; Alta., B.C., Man., N.B., Nfld., N.W.T., N.S., Ont., Que., Sask., Yukon; Alaska, Conn., Ill., Iowa, Maine, Md., Mass., Mich., Minn., N.H., N.J., N.Y., N.C., Ohio, Pa., R.I., Vt., Va., W.Va., Wis.; n Eurasia.
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Habitat
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Sporulating summer--early fall. Cliffs and rocky slopes; found on variety of substrates including serpentine; 0--1500m.
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Synonym
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Acrostichum ilvense Linnaeus, Sp. Pl. 2: 1071. 1753
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Woodsia ilvensis
provided by wikipedia EN
Woodsia ilvensis, commonly known as oblong woodsia,[3] is a fern found in North America and northern Eurasia. Also known as rusty woodsia or rusty cliff fern, it is typically found on sunny, exposed cliffs and rocky slopes and on thin, dry, acidic soils.[2][4][5][6]
Distribution
Its distribution is circumpolar. It is most abundant in Scandinavia, the Ural and Altai mountains and the eastern United States.[6] It is also found in Japan,[4] Alaska, Canada, coastal Greenland and various European locations including the Alps.
It is considered "Threatened" or "Endangered" in the states of Illinois, Iowa, and Maryland and "Presumed Extirpated" in Ohio.[1][2] Also found in West Virginia and North Carolina, it is the most common Woodsia species in the US.[5]
Its UK distribution is confined to Angus and the Moffat Hills in Scotland, north Wales and Teesdale and the Lake District in England.[6] There are fewer than 90 wild clumps in the whole of the UK, where it is on the edge of its natural range and is considered to be "Endangered".[6][7] For this reason it became a protected species in the UK in 1975 under the Conservation of Wild Creatures and Wild Plants Act.[8]
Discovery and identification
The plant was first identified as a separate species from specimens collected in Scotland in Bolton's 1785 publication Filices Britannica. Bolton distinguished between Acrostichum ilvense and Acrostichum alpina, now Woodsia ilvensis and Woodsia alpina respectively, which had previously been conflated.[6] The genus Woodsia was established in 1810 by Robert Brown, who named it after the English botanist Joseph Woods.[5][6] "Ilvensis" is the genitive form of the Latin name for the island of Elba.[4]
The leaves are typically 6 inches long and 1 inch wide, with stiff, erected pointed tips and cut into 12 nearly opposite stemless leaflets. The underside of the leaves are covered in white woolly fibres, which later turn rusty brown.[9]
Victorian collectors and modern conservation
Oblong woodsia came under severe threat from Victorian fern collectors in the mid 19th century in Scotland, especially in the Moffat Hills. These hills once had the most extensive UK populations of the species but there now remain only a few small colonies whose future is under threat. This period of collecting became known as pteridomania (or "fern-fever"). The Royal Botanic Garden Edinburgh plan to use cultivated specimens and a spore bank to restore depleted wild populations.[6]
References
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Woodsia ilvensis: Brief Summary
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Woodsia ilvensis, commonly known as oblong woodsia, is a fern found in North America and northern Eurasia. Also known as rusty woodsia or rusty cliff fern, it is typically found on sunny, exposed cliffs and rocky slopes and on thin, dry, acidic soils.
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