Hymenophyllum australe

Last updated

Austral filmy-fern
Close up of Hymenophyllum australe frond.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Plantae
Clade: Tracheophytes
Division: Polypodiophyta
Class: Polypodiopsida
Order: Hymenophyllales
Family: Hymenophyllaceae
Genus: Hymenophyllum
Species:
H. australe
Binomial name
Hymenophyllum australe
Synonyms

Mecodium australe Hymenophyllum atrovirens

Hymenophyllum australe, commonly known as austral filmy fern, [1] is a relatively large rupestral and epiphytic fern, indigenous to eastern Australia [2] and New Zealand. [3] It belongs to the unique Hymenophyllum genus (filmy ferns), 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. [2] Hymenophyllum australe is distinctive in that the fronds are typically thicker than other Hymenophyllum species, often being up to 2-3 cells thick. [4] [5]

Contents

Hymenophyllum australe is inconspicuous and will typically form matted patches together with mosses and liverworts. [1] In Australia it takes on an epiphytic approach, commonly seen to clothe roots, trunks and rocks to form a dense mat of foliage; [1] while in New Zealand it adopts a more rheophytic approach, preferring rocks or tree trunks in or close to water. [3] [6]

It has dark green fronds, which are distinctly deltoid in shape, with entire ultimate segment margins, each containing a single conspicuous vein. [2] It is recognised by its winged fronds, which are initially relatively broad (several millimetres wide) but gradually taper from the rachis along the stipe. [7]

Description

Hymenophyllum australe are rupestral or epiphytic ferns. The rhizomes are long-creeping, fine (typically 0.2-0.5 mm in diameter), branched and possess bare scattered hairs typically clustered near the base of the stipe. [3] [2] Stomata are absent. [2]

Characteristic of the Hymenophyllum genus, the sori are terminal on segments (see sketch below) and encompass a two-lipped indusium (protective cover), [8] which often has notched margins. [1] The sori are numerous and borne singly or paired. [2] The receptacle is short and enclosed within indusial flaps. The species is homosporous, [3] with spores trilete, greenish and slightly roughened. [8]

The stipes are winged almost to the base, often crinkled and emanate at intervals along the rhizome. [1] [2] [9] The fronds are dark green, dull and membranous, ranging in size from 38–210 mm long; [2] they are triangular to ovate in shape and pinnate to tripinnate. [1] The rachises are winged, glabrous, dark brown proximally and pale brown distally. [3] The ultimate lamina segments are narrowly oblong and have a spreading finger-like appearance; the margins are entire, with each ultimate segment containing a single conspicuous vein. [9] [3]

Taxonomy and naming

Hymenophyllum australe was first formally described in 1810 by Carl Ludwig Willdenow in the published Species Plantarum Edition 4, [10] [11] under the basionym of Mecodium australe . [9] [11]

The botanical genus name Hymenophyllum is derived from the Greek hymen, meaning membrane, and phyllon, a leaf, referring to the delicate membranous leaf, [2] while the specific epithet, australe, is derived from the Latin australis, meaning southern, in reference to its occurrence in Australia and New Zealand. [3]

Notably, New Zealand populations of Hymenophyllum australe were previously divided into a separate species, Hymenophyllum atrovirens, and interpreted as endemic to New Zealand. [12] [13] However, given the absence of distinguishable morphological characters, [5] in addition to recent molecular evidence demonstrating pronounced similarity of the chloroplast DNA sequences of the Australian and New Zealand ferns, [7] Hymenophyllum atrovirens is now considered conspecific with Hymenophyllum australe. [3]

Hymenophyllum atrovirens was initially described in 1845 by English botanist William Colenso in his collections from Lake Waikaremoana in 1841. [14] [7]

Distribution

Hymenophyllum australe is a common fern species of eastern Australia, principally located in the rainforests and fern gullies. It is present in Victoria, from the Otways through to Gippsland [2] and was formally present on the Mornington Peninsula, but recently appears extinct in this area owing to bushfires. [15]

It is also found in Tasmania, southern Queensland and New South Wales, in particular the Blue Mountains area. [2] [1] Hymenophyllum australe is also present on both the north and south islands of New Zealand, although there it is less common than in Australia.

In Tasmania and New Zealand it has been noted the wings of the fronds are typically smaller and the segments less wrinkled. [9]

Sketch of Hymenophyllum australe frond. Highlighting the single conspicuous single vein in each ultimate segment and terminal sori. Anotated H.australe Frond.jpg
Sketch of Hymenophyllum australe frond. Highlighting the single conspicuous single vein in each ultimate segment and terminal sori.
Hymenophyllum australe, picture by Robert Wiltshire. Hymenophyllum australe from a distance.jpg
Hymenophyllum australe, picture by Robert Wiltshire.

.

Regions in New Zealand where Hymenophyllum australe has been recognised
North Island Northland, Auckland, Volcanic Plateau, Gisborne, Taranaki, Southern North Island [3]
South IslandWestern Nelson, Canterbury, Otago, Fiordland, Stewart Island [3]
Regions in Australia where Hymenophyllum australe has been recognised
Victoria Gippsland Plain, Otway Plain, Otway Ranges, Warrnambool Plain, Central Victorian Uplands, East Gippsland Lowlands, East Gippsland Uplands, Wilsons Promontory, Highlands-Southern Fall, Highlands-Northern Fall, Strzelecki Ranges, Highlands-Far East, Victorian Alps [15]
QueenslandSouth-east [2]
New South Wales North Coast, Central Coast, South Coast, Central Tablelands [16]
Tasmania Tasmanian Southern Ranges, Tasmanian West, Tasmanian South East, Ben Lomond, Circular Head, Tasmanian Northern Slopes, Furneaux, Tasmanian Central Highlands [17]

Habitat

Filmy ferns are typically small in size and limited to wet or misty areas due to the thin, delicate nature of their fronds. [1] [18] Water is rapidly lost under a dry atmosphere and in consequence Hymenophyllum australe will shrivel and collapse [1] as filmy-ferns possess no strengthening tissues in their fronds; being entirely dependent on water pressure to maintain turgidity. [4] As a result, these fragile ferns grow optimally where the air is moist. [18]

In New Zealand, Hymenophyllum australe is heavily constrained to growing on rocks, or rarely low on tree trunks, either partially submerged or close to flowing water in shaded habitats. [3] It almost displays a rheophytic habit and is seldom found away from waterways. [6]

Conversely in Australia the species grows in a much broader range of habitats, expanding to rock further away from water and additionally as an epiphyte. [3] [1] It is common to wet forests and routinely forms curtains on tree-trunks, logs, wet rocks or on the walls of caves, given there is sufficient light present. [1] In Australia, Hymenophyllum australe is found to display a strong association with tree-fern trunks, commonly perceived to adorn tree-ferns from top to bottom. [8] In Tasmania, Hymenophyllum australe was found to exhibit a significant preference to grow on the trunks of the more prevalent Dicksonia antarctica than the trunks of the rarer Cyathea cunninghamii tree-ferns. [19]

Reproduction

Sexual reproduction

Like all ferns, Hymenophyllum australe has a life cycle with two distinct phases: a minor haploid gametophyte stage, which grows from spores and produces the gametes, and a sporophyte stage which is diploid and yields spores from the sporangia. [1]

The gametophytic generation begins with the formation of spores from the sporangia on the leaf of a sporophyte, under favourable conditions (adequate moisture, temperature, pH range and light intensity [20] ) these spores will germinate and subsequently develop into a filamentous prothallus (or gametophyte). [2]

The prothallus in Hymenophyllum australe (including all Hymenophyllum species) is long and narrow and often referred to as ribbon-like. [21] [22] This is atypical of the archetypal heart-shaped prothallus seen in other ferns. [22] [4] The prothallus harbours sporadic marginal archegonial cushions [22] and this is where the archegonia are borne, while the antheridia are borne on slender branches on the basal margins of the prothallus. [21]

In the presence of water, spores germinate following a typical fern progression, with the antheridia trapped under the prothallus bursting to release the sperm cells. A chemical signal (sperm chemotaxis) is released from the archegonia which attracts the motile sperm cells towards it. Once the sperm cells reach the archegonium, they open and enable the male gamete to travel down to the ovum, with which it unites to induce fertilisation and form a zygote.

This fertilised zygote is diploid and develops into an embryo and sporophyte, or ‘true fern’ that is most readily recognised, while remaining embedded in the prothallus. The sporophyte is dependent on the prothallus for nutrition (parasitic) until the embryo forms its first roots and leaves, whereupon the sporophyte becomes independent and the prothallus subsequently dies. [2] The cycle is complete when spores are produced on the sporophyte.

Notably, as in all ferns, water is required for successful sexual reproduction, with the fusion of the gametes entirely dependent on the availability of free water. [2]

Asexual reproduction

Both gametophytes and sporophytes are capable of vegetative reproduction. In the gametophyte stage this is typically through regeneration of fresh prothalli from older ones, but it can also occur through gemmae which are more organised means of vegetative propagation. [22]

It has been recognised that adverse growing conditions, such as drying, promotes abundant formation of gemmae, as vegetative reproduction does not involve the fusion of gametes and hence does not require water. [22]

Conservation status

Hymenophyllum australe in Australia is considered locally common within its preferred growing conditions. [23] [24] [25] However, in New Zealand the conservation status of Hymenophyllum australe was reassessed in 2012 using the New Zealand Threat Classification System (NZTCS) to be "at risk to naturally uncommon". [26]

Cytology

Chromosome number = 36 (N=36). [27]

Related Research Articles

<span class="mw-page-title-main">Gametophyte</span> Haploid stage in the life cycle of plants and algae

A gametophyte is one of the two alternating multicellular phases in the life cycles of plants and algae. It is a haploid multicellular organism that develops from a haploid spore that has one set of chromosomes. The gametophyte is the sexual phase in the life cycle of plants and algae. It develops sex organs that produce gametes, haploid sex cells that participate in fertilization to form a diploid zygote which has a double set of chromosomes. Cell division of the zygote results in a new diploid multicellular organism, the second stage in the life cycle known as the sporophyte. The sporophyte can produce haploid spores by meiosis that on germination produce a new generation of gametophytes.

<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.

<span class="mw-page-title-main">Alternation of generations</span> Reproductive cycle of plants and algae

Alternation of generations is the predominant type of life cycle in plants and algae. In plants both phases are multicellular: the haploid sexual phase – the gametophyte – alternates with a diploid asexual phase – the sporophyte.

<span class="mw-page-title-main">Prothallus</span> Gametophyte stage in the fern life cycle

A prothallus, or prothallium, is usually the gametophyte stage in the life of a fern or other pteridophyte. Occasionally the term is also used to describe the young gametophyte of a liverwort or peat moss as well. In lichens it refers to the region of the thallus that is free of algae.

Plant reproduction is the production of new offspring in plants, which can be accomplished by sexual or asexual reproduction. Sexual reproduction produces offspring by the fusion of gametes, resulting in offspring genetically different from either parent. Asexual reproduction produces new individuals without the fusion of gametes, resulting in clonal plants that are genetically identical to the parent plant and each other, unless mutations occur.

<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>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>Hymenophyton flabellatum</i> Species of liverwort

Hymenophyton flabellatum is a species of the order Pallaviciniales (liverworts), one of perhaps several species in the genus Hymenophyton. It is a dendroid thalloid liverwort belongs to the family Hymenophytaceae and is commonly known as Fan liverwort. It is found in New Zealand, Chile, and common in wet forests of Australia and Tasmania. Hymenophyton flabellatum closely resembles with small filmy fern, Hymenophyllum and can be confused with the liverwort, Symphyogyna hymenophyllum.

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

Diplazium australe, commonly known as the Austral lady fern, is a small fern occurring in eastern Australia, New Zealand and Norfolk Island. The habitat is moist shaded areas, often occurring in rainforest.

<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>Aglaomorpha</i> (plant) Genus of ferns

Aglaomorpha is a genus of ferns in the subfamily Drynarioideae of the family Polypodiaceae. The Pteridophyte Phylogeny Group classification of 2016 uses this genus name, while other sources use Drynaria to include Aglaomorpha. Species are commonly known as basket ferns. As circumscribed in PPG I, the genus contains around 50 species.

<i>Hypnodendron comosum</i> Species of moss

Hypnodendron comosum, commonly known as palm moss or palm tree moss, is a ground moss which can be divided into two varieties: Hypnodendron comosum var. comosum and Hypnodendron comosum var. sieberi. Both Hypnodendron varieties most commonly grow in damp locations in the temperate and tropical rainforests of New South Wales, Victoria, and Tasmania in southern Australia and in New Zealand.

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

Hymenophyllum tunbrigense, the Tunbridge filmy fern or Tunbridge filmy-fern, 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.

Tasmania is home to 'Australia’s largest cool temperate rainforests. Most of Tasmania’s rainforests occur in the North-West and throughout the North East highlands. Cool temperate rainforests typically have a heavy rainfall, cool climate, favor high altitudes and have a limited availability of light.

<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.

<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.

<i>Symphyogyna podophylla</i> Liverwort species

Symphyogyna podophylla is a dendroid liverwort which is widespread in wet forests. It occurs in New Zealand, South America, Southern Africa, and is very common in wet forests of Australia and Tasmania.

<i>Telmatoblechnum serrulatum</i> Species of fern

Telmatoblechnum serrulatum, the toothed midsorus fern, is a species of fern in the family Blechnaceae, native to Florida, southeastern Mexico, Central America, the Caribbean, northern and western South America, Brazil, Paraguay, and northeastern Argentina.

References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 Jones, David L; Clemesha, Steven C (1976). Australian ferns and fern allies. Terrey Hills: Reed Publishing Ltd. pp. 9, 8, 64, 69, 70. ISBN   0589071971.
  2. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Duncan, Betty D; Isaac, Golda (1986). Ferns and allied plants of Victoria, Tasmania and South Australia. Australia: Melbourne University Press. pp. 2, 3, 78, 81, 83, 84. ISBN   0522842623.
  3. 1 2 3 4 5 6 7 8 9 10 11 12 Brownsey, Patrick J; Perrie, Leon R (2016). Flora of New Zealand: Hymenophyllaceae. Lincoln, New Zealand: Manaaki Whenua Press. pp. 8–10. doi:10.7931/B1QP4Z. ISBN   9780478347876.
  4. 1 2 3 Garrett, M. (1986, December). "Fairies of the Fern World", Newsletter Number 35, pp. 9. Retrieved from URL (https://www.verdigris.com.au/default.aspx?hid=310)
  5. 1 2 Ebihara, Atsushi; Nitta, Joel H (2010). "The Hymenophyllaceae of the Pacific Area. 2. Hymenophyllum (Excluding Subgen. Hymenophyllum)" (PDF). Bulletin of the National Museum of Nature and Science. Series B, Botany. 36: 51 via Kahaku.
  6. 1 2 "Hymenophyllum australe | New Zealand Plant Conservation Network". www.nzpcn.org.nz. Retrieved 2019-12-07.
  7. 1 2 3 Perrie, LR; Shepherd, LD; de Lange, PJ; Batty, EL; Ohlsen, DJ; Bayly, MJ; Brownsey, PJ (2013). "Hymenophyllum pluviatile, a new and uncommon fern from New Zealand". New Zealand Journal of Botany. 51 (4): 308–320. doi: 10.1080/0028825x.2013.834830 . ISSN   0028-825X. S2CID   86753654.
  8. 1 2 3 Andrews, S B (1990). Ferns of Queensland: A handbook to the ferns and fern allies. Queensland: Queensland Department of Primary Industries. p. 177. ISBN   0724232249.
  9. 1 2 3 4 Wakefield, Norman Arthur; Willis, James Hamlyn (1975). Ferns of Victoria and Tasmania. Melbourne: Field Naturalists Club of Victoria. pp. 3, 5. ISBN   0959807411.
  10. Linné, Carl von; Willdenow, Karl Ludwig; Link, Heinrich Friedrich; Schwägrichen, Christian Friedrich; Nauck (Firm), G. C. (1797–1830). Caroli a Linné Species plantarum :exhibentes plantas rite cognitas, ad genera relatas, cum differentiis specificis, nominibus trivialibus, synonymis selectis, locis natalibus, secundum systema sexuale digestas. Vol. v.5:pt.1 (Ed. 4., post Reichardianam quinta ed.). Berolini: Impensis G.C. Nauk.
  11. 1 2 "Vascular Plants". biodiversity.org.au. Retrieved 2019-12-07.
  12. Allan, H. H. (Harry Howard), 1882-1957. (1982). Flora of New Zealand. Psilopsida, Lycopsida, Filicopsida, Gymnospermae, Dicotyledones. Government Printer. ISBN   0-477-01056-3. OCLC   760926043.{{cite book}}: CS1 maint: multiple names: authors list (link)
  13. Brownsey, P. J.; Given, D. R.; Lovis, J. D. (1985). "A revised classification of New Zealand pteridophytes with a synonymic checklist of species". New Zealand Journal of Botany. 23 (3): 431–489. doi: 10.1080/0028825x.1985.10425348 . ISSN   0028-825X.
  14. Colenso, W. (1845). A classification and description of some newly-discovered ferns : collected in the northern island of New Zealand in the summer of 1841-2 /. Launceston, V.D. Land: Printed at the office of the Launceston examiner. doi:10.5962/bhl.title.132534.
  15. 1 2 "Flora of Victoria". vicflora.rbg.vic.gov.au. Retrieved 2019-12-07.
  16. "PlantNET - FloraOnline". plantnet.rbgsyd.nsw.gov.au. Retrieved 2019-12-07.
  17. Herbaria, jurisdiction:Australian Government Departmental Consortium;corporateName:Council of Heads of Australasian. "Partners". avh.ala.org.au. Retrieved 2019-12-07.{{cite web}}: CS1 maint: multiple names: authors list (link)
  18. 1 2 Chinnock, R J; Heath, Eric W (1987). Common Ferns and Fern Allies in New Zealand. Auckland, New Zealand: Reed Methuen Publishers Ltd. p. 28. ISBN   0474002934.
  19. ROBERTS, Nina R.; Dalton, Patrick J.; Jordan, Gregory J. (2005). "Epiphytic ferns and bryophytes of Tasmanian tree-ferns: A comparison of diversity and composition between two host species" (PDF). Austral Ecology. 30 (2): 146–154. doi:10.1111/j.1442-9993.2005.01440.x. ISSN   1442-9985.
  20. Miller, John H. (1968). "Fern gametophytes as experimental material". The Botanical Review. 34 (4): 361–440. doi: 10.1007/bf02859133 . ISSN   0006-8101. S2CID   32581094.
  21. 1 2 Stone, IG (1965). "The gametophytes of the Victorian Hymenophyllaceae". Australian Journal of Botany. 13 (2): 195. doi:10.1071/bt9650195. ISSN   0067-1924.
  22. 1 2 3 4 5 Nayar, B K; Kaur, S (1971). "Gametophytes of Homosporous Ferns". Botanical Review. 37 (3): 356–359, 376. doi:10.1007/BF02859157. JSTOR   4353813. S2CID   12733899.
  23. ".: Hymenophyllum australe". fe.yarraranges.vic.gov.au. Retrieved 2019-12-07.
  24. "Flora Recovery Plan: Threatened Tasmanian Ferns" (PDF). Department of the Environment and Energy. Retrieved 2019-12-07.
  25. Environment, jurisdiction=Commonwealth of Australia; corporateName=Department of the. "Threatened Species List". www.environment.gov.au. Retrieved 2019-12-07.{{cite web}}: CS1 maint: multiple names: authors list (link)
  26. De Lange, Peter J. (Peter James), author. Conservation status of New Zealand indigenous vascular plants, 2012. OCLC   992779428.{{cite book}}: |last= has generic name (help)CS1 maint: multiple names: authors list (link)
  27. Brownlie, G. Chromosome numbers in some Pacific Pteridophyta. OCLC   79659531.

Further reading