Hymenophyllum tunbrigense

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Tunbridge filmy fern
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Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Plantae
Clade: Tracheophytes
Division: Polypodiophyta
Class: Polypodiopsida
Order: Hymenophyllales
Family: Hymenophyllaceae
Genus: Hymenophyllum
Species:
H. tunbrigense
Binomial name
Hymenophyllum tunbrigense
(L.) Sm.
Synonyms

Trichomanes tunbrigenseL.

Hymenophyllum tunbrigense, the Tunbridge filmy fern [1] or Tunbridge filmy-fern, [2] is a small, fragile perennial leptosporangiate fern which forms large dense colonies of overlapping leaves from creeping rhizomes. The common name derives from the leaves which are very thin, only a single cell thick, and translucent, giving the appearance of a wet film. The evergreen fronds are bipinnatifid, deeply and irregularly dissected, about 3 to 6 cm long, 2 cm across with dark winged stipes. In contrast to the similar H. wilsonii the fronds are more divided, flattened, appressed to the substrate and tend to have a bluish tint.

Contents

The fronds are monomorphic and produce sori along the frond segments close to the rachis. Up to 5–10 purse-shaped sori are produced per frond, each covered by two strongly convex, flattened indusial valves. The valve margins are jagged and used to distinguish H. tunbrigense from H. wilsonii , where the edges are entire.

In common with all ferns, H. tunbrigense exhibits a gametophyte stage in its life cycle (alternation of generations) and develops a haploid reproductive prothallus as an independent plant. Information about the gametophyte is scarce but it is likely to be inconspicuous with a narrow ribbon-like thallus. [3] The gametophyte may be able to reproduce itself vegetatively by gemmae in the absence of the sporophyte. Gametophytes of the related Killarney fern ( Trichomanes speciosum ) have been found outside the geographical range of the sporophyte [4] and this may prove to be true of Hymenophyllum tunbrigense.

Taxonomy

The basionym for the species is Trichomanes tunbrigense, published by Linnaeus in Species Plantarum in 1753, based on material from England and Italy. One of the descriptions he cited was that of James Petiver, [5] who collected it near Tunbridge Wells and described it as Darea tunbrigensis minor, in honor of George Dare who had collected it from the same locality. [6] James Edward Smith, in the third volume of English Botany , transferred it to the genus Hymenophyllum in 1794, based on the two-valved indusium (rather than the tubular indusium of Trichomanessensu stricto). [7]

Distribution

Apparently worldwide, but discontinuous, in distribution but most frequent in western European oceanic regions like the British Isles. There is uncertainty whether similar plants found in Mexico, the West Indies, Central America, South America, South Africa and Asia should also be included in this species. H. tunbrigense has a similar though distinct distribution to H. wilsonii and can also be found in North America. Its habitat preference may mean that it has been under-recorded in many less-well populated parts of the world.

In continental Europe it occurs much further east than H. wilsonii but these sites are very disjunct and may represent relict populations from a different climatic period. Many of the continental populations are declining or have disappeared in recent times.

The specific name is derived from Royal Tunbridge Wells in Kent, England which was one of its disjunct eastern localities in Britain.

Ecology and conservation

Filmy ferns ( Hymenophyllum species, Trichomanes species) are very vulnerable to desiccation which limits the habitats in which they can survive. Hymenophyllum species are dependent as much, or more, upon the microclimate of a site as the macroclimate. H. tunbrigense is usually associated with rock outcrops, especially when deep fissures or crevices are present.

Hymenophyllum tunbrigense appears not to reproduce effectively from spores under present environmental conditions. Gametophytes have not been identified in the field although there is circumstantial evidence that sexual reproduction does take place. [8]

Cultivation and uses

While there are records of its cultivation (Harold Stuart Thompson grew a specimen from Somerset in a bell jar in his bedroom for a decade), [9] it is not generally cultivated. It is propagated at Kew Gardens for reestablishment in suitable habitat. [10]

Related Research Articles

<span class="mw-page-title-main">Fern</span> Class of vascular plants

The ferns are a group of vascular plants that reproduce via spores and have neither seeds nor flowers. They differ from mosses by being vascular, i.e., having specialized tissues that conduct water and nutrients and in having life cycles in which the branched sporophyte is the dominant phase.

<i>Platycerium</i> Genus of ferns

Platycerium is a genus of about 18 fern species in the polypod family, Polypodiaceae. Ferns in this genus are widely known as staghorn or elkhorn ferns due to their uniquely shaped fronds. This genus is epiphytic and is native to tropical and temperate areas of South America, Africa, Southeast Asia, Australia, and New Guinea.

<i>Gymnocarpium dryopteris</i> Species of fern

Gymnocarpium dryopteris, the western oakfern, common oak fern, oak fern, or northern oak fern, is a deciduous fern of the family Cystopteridaceae. It is widespread across much of North America and Eurasia. It has been found in Canada, the United States, Greenland, China, Japan, Korea, Russia, and most of Europe. It is a seedless, vascular plant that reproduces via spores and have a life cycle with alternating, free-living sporophyte and gametophyte phases.

<span class="mw-page-title-main">Hymenophyllaceae</span> Family of ferns

The Hymenophyllaceae, the filmy ferns and bristle ferns, are a family of two to nine genera and about 650 known species of ferns, with a subcosmopolitan distribution, but generally restricted to very damp places or to locations where they are wetted by spray from waterfalls or springs. A recent fossil find shows that ferns of Hymenophyllaceae have existed since at least the Upper Triassic.

<i>Trichomanes</i> Genus of ferns

Trichomanes is a genus of ferns in the family Hymenophyllaceae, termed bristle ferns. The circumscription of the genus is disputed. All ferns in the genus are filmy ferns, with leaf tissue typically 2 cells thick. This thinness generally necessitates a permanently humid habitat, and makes the fronds somewhat translucent. Because of this membrane-like frond tissue, the plant is prone to drying out. “Filmy ferns” in the taxa Hymenophyllaceae grow in constantly wet environments. Many are found in cloud forests such as “Choco” in Colombia. There are also members of the taxa that can grow submersed in water.

<i>Hymenophyllum nephrophyllum</i> Species of fern

Hymenophyllum nephrophyllum, the kidney fern, is a filmy fern species native to New Zealand. It commonly grows on the forest floor of open native bush. Individual kidney-shaped fronds stand about 5–10 cm tall. In hot weather they shrivel up to conserve moisture, but open up again when the wet returns. This species has very thin fronds which are only four to six cells in thickness. In the Māori language they are also called raurenga.

<i>Vandenboschia speciosa</i> Species of fern

Vandenboschia speciosa, synonym Trichomanes speciosum, commonly known as the Killarney fern, is a species of fern found widely in Western Europe. It is most abundant in Ireland, Great Britain, Brittany, Galicia, Canary Islands, Madeira and the Azores, but is also found in other locations including France, Spain, Portugal and Italy. It is a relict endemic European species with a disjunct distribution, having had a much wider distribution before the climate changes of the Tertiary and Quaternary periods.

<i>Asplenium trichomanes</i> Species of fern in the family Aspleniaceae

Asplenium trichomanes, the maidenhair spleenwort, is a small fern in the spleenwort genus Asplenium. It is a widespread and common species, occurring almost worldwide in a variety of rocky habitats. It is a variable fern with several subspecies.

<i>Aspidotis densa</i> Species of fern

Aspidotis densa is a species of fern in the Cheilanthoid subfamily, known by the common name Indian's dream or Serpentine fern or dense lace fern. It is native to the west coast of North America from British Columbia to California and east to the Rocky Mountains in Idaho, Montana, and Wyoming; there is a disjunct population on serpentine soils in Quebec.

<i>Crepidomanes intricatum</i> Species of fern

Crepidomanes intricatum, synonym Trichomanes intricatum, is known as the weft fern. The genus Crepidomanes is accepted in the Pteridophyte Phylogeny Group classification of 2016, but not by some other sources. As of October 2019, Plants of the World Online sank the genus into a broadly defined Trichomanes, treating this species as Trichomanes intricatum.

<i>Hymenophyllum australe</i> Species of fern

Hymenophyllum australe, commonly known as austral filmy fern, is a relatively large rupestral and epiphytic fern, indigenous to eastern Australia and New Zealand. It belongs to the unique Hymenophyllum genus, which are characterised by their thin membranous fronds that are seldom more than one cell thick, with the exception of regions over and around veins. Hymenophyllum australe is distinctive in that the fronds are typically thicker than other Hymenophyllum species, often being up to 2-3 cells thick.

<i>Hymenophyllum flabellatum</i> Species of plant

Hymenophyllum flabellatum, the shiny filmy-fern, is a species of fern in the family Hymenophyllaceae. This delicate fern is commonly epiphytic and is between 5 and 25 cm in length. It is distinct, with its thin, one-celled thick, membranous leaves. It is from the family Hymenophyllaceae and is dispersed world wide. The species is dispersed highly throughout Tasmanian rainforests and in the south east of mainland Australia, with small pockets of the population seen in northern Queensland.

<i>Gymnocarpium robertianum</i> Species of fern

Gymnocarpium robertianum, the limestone fern or scented oakfern, is a fern of the family Cystopteridaceae.

Michael Charles Faraday Proctor PhD was an English botanist and plant ecologist, lecturer, scientific author based at the University of Exeter. He retired from his post as Reader in Plant Ecology at Exeter University in 1994.

<i>Hymenophyllum wilsonii</i> Species of fern

Hymenophyllum wilsonii, the Wilson's filmy-fern, is a small, fragile, perennial leptosporangiate fern which forms large dense colonies from creeping rhizomes.

<i>Vandenboschia boschiana</i> Species of fern

Vandenboschia boschiana, synonym Trichomanes boschianum, also known as the Appalachian bristle fern or Appalachian filmy fern, is a small delicate perennial leptosporangiate fern which forms colonies with long, black creeping rhizomes.

<i>Polyphlebium venosum</i> Species of fern

Polyphlebium venosum, the veined bristle-fern or bristle filmy fern, is a fern in the family Hymenophyllaceae. It is only found in wet forests, mainly growing as an epiphyte on the shady side of the soft tree fern, Dicksonia antartica. It also grows on logs, trunks of trees and rarely on trunks of Cyathea species or on wet rock-faces. It is found in the wetter parts of Eastern Australia and New Zealand. P. venosum has poor long-distance dispersal compared to other ferns due to its short lived spore. Notable features of Polyphlebium venosum include it being one cell layer thick, 5–15 cm in length, having many branching veins and a trumpet shaped indusium.

Mary Agnes Stump Taylor (1885-1976) was an American bryologist noted for collecting and identifying many species of bryophytes across North America. Her collection of around 8,000 plants was so extensive that it has been used to identify the range of plants several decades after their original collection. The standard author abbreviation M.S.Taylor is used to indicate this person as the author when citing a botanical name.

<i>Hymenophyllum rarum</i> Species of plant

Hymenophyllum rarum, the narrow filmy-fern, is a species of fern from the family Hymenophyllaceae. This thin-leaved fern is commonly found in New Zealand and Tasmania, growing in patches on rocks and is epiphytic on trees and tree ferns, growing in moist gullies or rainforests. A rather drought tolerant species often found at exposed sites ranging from coastal to montane areas. Forming extensive, interwoven and creeping patches with its thin long (creeping) rhizomes sparsely covered in red-brown hairs, easily recognised by its membranous grey-green fronds, the smooth margins of the pinnae, ultimate segments and indusia; and by the sunken sori in the uppermost segments of the uppermost pinnae. The species can be found throughout Tasmanian rainforests as well as occurring in New South Wales, Victoria and New Zealand on the North and South Islands as well as, Stewart, Chatham and Auckland Islands.

<i>Hymenophyllum peltatum</i> Species of fern

Hymenophyllum peltatum, is a species of filmy fern widely distributed across Australia, New Zealand, South Africa, South America. Predominantly a rainforest species with delicate foliage arrangements, also known as the 'alpine filmy-fern'. Members of the Hymenophyllaceae family display almost translucent fronds, bearing thickness of just a single cell.

References

  1. USDA, NRCS (n.d.). "Hymenophyllum tunbrigense". The PLANTS Database (plants.usda.gov). Greensboro, North Carolina: National Plant Data Team. Retrieved 22 January 2016.
  2. BSBI List 2007 (xls). Botanical Society of Britain and Ireland. Archived from the original (xls) on 2015-06-26. Retrieved 2014-10-17.
  3. Stokey, A.G. (1940). Spore Germination and Vegetative Stages of the Gametophytes of Hymenophyllum and Trichomanes. Bot Gaz 101: 759
  4. Rumsey, F.J., Sheffield, E., Farrar, D.R (1990) British Filmy-fern gametophytes. Pteridologist 2: pp. 40–42
  5. Linnaeus, C. (1753). Species Plantarum. Vol. II. Stockholm: Laurentii Salvii. p. 1098.
  6. Petiver, James (1695). Musei Petiveriani centuria prima. London: S. Smith & B. Walford. p.  73.
  7. Smith, James Edward (1794). English Botany. Vol. 3. illustrated by James Sowerby. London: J. Davis. p. 162.
  8. Richards, P.W., Evans, G.B. (1972). Biological Flora of the British Isles. No. 126. Hymenophyllum tunbrigense (L.) Sm. (pp. 245–258), Hymenophyllum wilsonii Hooker (258–268). Journal of Ecology 60.
  9. H.S. Thompson s.n., August 1886, http://herbariaunited.org/specimen/259752/
  10. "Hymenophyllum tunbrigense (Tunbridge filmy fern)". Royal Botanic Gardens Kew. Retrieved 8 October 2016.

Further reading

Page, C.N. (1997). The ferns of Britain and Ireland. 2nd Ed. Cambridge University Press. Cambridge.

Proctor, M.C.F. (2003). Comparative Ecophysiological Measurements on the Light Responses, Water Relations and Desiccation Tolerance of the Filmy Ferns Hymenophyllum wilsonii Hook. and H. tunbrigense (L.) Smith Ann Bot 91 (6).

Richards, P.W., Evans, G.B. (1972). Biological Flora of the British Isles. No. 126. Hymenophyllum tunbrigense (L.) Sm. (pp. 245–258), Hymenophyllum wilsonii Hooker (258–268). Journal of Ecology 60.