Nest fern
| Nest fern | ||||||||||||
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Nest fern ( Asplenium nidus ) |
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| Asplenium nidus | ||||||||||||
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The nest fern ( Asplenium nidus ) is a species of the striped fern family (Aspleniaceae).
description
The epiphytically growing nest fern forms a dense rosette of leaves (fern fronds) from a short and strong upright or ascending, woody rhizome . A dense tangle of aerial roots also arises from the rhizome. It is covered by dark to purple-brown scales, these are triangular to linear-subleaf and membranous, they reach about two centimeters in length and weather like a network. The leaves are short-stalked (also sessile in Hawaiian plants), the woody stem, semicircular in cross-section, is two to five centimeters long, light brown or straw-colored, and scaly at the base. The paper-thin to slightly leathery leaf blade is simple and undivided with a smooth edge, it is broadly lanceolate, widest in the middle and gradually narrows towards both the stem and the apex. It reaches 90 to 120 centimeters in length, in individual cases even more, with a width of 12 to 15, sometimes up to 30 centimeters. In particular, spore-bearing leaves are often narrower and then only reach about six centimeters wide. The apex is pointed to pointed. The leaves are grass to fresh green on the upper side, the underside is noticeably lighter in color. The leaf veins are only single, rarely double, branched, with the first branching approximately in the middle of the frond. The veins run parallel to each other, they reunite along the leaf margin to form a marginal vein. The midrib of the leaf is protruding on the upper side, but flat on the underside. The Sori are linear along the leaf veins (on the side towards the apex), from the midrib to about the middle of the leaf blade, they reach about three to five centimeters in length. The basal half of the fronds is usually sterile, sori are located in the fertile part on almost every vein. The veil ( Indusium ) of the Sori is very narrowly linear and brown in color, it is entire and permanent.
The species can be distinguished from related and similar species (section Thamnopteris ) as follows: In Asplenium australasicum and Asplenium pacificum , the rosette of leaves is narrower and steeper, steeply funnel-shaped, while the fronds of Asplenium nidus initially descend horizontally and then gradually incline upwards a nest-shaped rosette results (name: Latin nidus, nest). In Asplenium musifolium , the apex of the leaf blade is broadly rounded, not pointed. However, some taxonomists regard all of these species names as synonyms for a broad species Asplenium nidus . For the taxonomy of the group see below.
The species is usually tetraploid . The number of chromosomes is 2n = 144.
Biology and ecology
The nest fern grows on the branches of trees, as an epiphyte , or more rarely perched on rocks (epilithic, lithophyte ). The densely matted root masses of the species also offer growth opportunities for other epiphytic plant species. In parts of the distribution area, such as Malaysia, it is considered the most common epiphytic fern species, possibly the most common epiphyte at all. It grows at all heights, from ground level to the crowns of the tallest trees, whereby nest ferns can be found in secondary forests as well as in oil palm plantations. In the primary forest, densities of 180 plants per hectare of forest were achieved, which then achieve a biomass of over one tonne dry weight. The funnel-shaped fronds catch rainwater and plant litter, which supply the plant with nutrients. A single leaf funnel can thus weigh up to 200 kilograms. Each of these funnels forms a miniature ecosystem, a microcosm in which numerous, specialized species live. Three quarters of the individuals in a funnel are ants, each of which can have multiple species coexisting, but never multiple nests of the same species.
A study on Luzon , Philippines, showed the great importance of the nest fern as a habitat for tree-living frog species. Five frog species, Philautus surdus , Platymantis luzonensis , P. banahao , P. montanus , and Polypedates leucomystax were found in 150 fern individuals examined . The fern funnels provide the frogs with cool and moist microhabitats in an otherwise often dry habitat that is therefore unfavorable for frogs.
distribution
The nest fern has its natural distribution in the rainforests of East Africa (including the island of Madagascar), tropical Asia , east to Japan, Australia and Polynesia . It grows from sea level to low mountain ranges of around 1700 meters, in China up to 1900 meters, mostly over 250 meters. The nest fern also occurs on mangroves on the seashore.
use
The nest fern is a popular houseplant . The species needs warm and moist, but not too wet, substrate. It thrives in bright places but shouldn't be exposed to direct sunlight. The species tolerates temperatures down to freezing point and even very light frosts. In Taiwan , the nest fern is also grown as a vegetable ( 山 蘇 , shān sũ ). There it is considered a traditional dish of the indigenous peoples of the mountainous region.
Taxonomy
The nest fern belongs in the genus Asplenium in the section Thamnopteris Presl ( synonym Neottopteris J.Sm. ). This includes a number of tropical, mostly epiphytic species with an upright, slowly growing rhizome that carries a number of seated or almost seated fronds in a tight spiral, so that, as a rule, a nest- or funnel-shaped growth form results. The fronds have a marginal vein and elongated sori with a narrow indusium. Due to the relatively simple, low-feature shape and the often widespread distribution, most of the species in the section are taxonomically problematic. It has been suspected for a long time that forms that are not necessarily closely related may have developed a similar growth form convergent to one another. This has been confirmed by phylogenomic studies in which the relationship is determined by comparing homologous DNA sequences. Accordingly, the form taxon Asplenium nidus is not a monophyletic unit; forms designated by this name from different parts of the distribution area are not closely related to one another. The necessary splitting of the “species” has not yet been carried out taxonomically.
Individual evidence
- ^ Daniel Dooley Palmer: Hawai'i's Ferns and Fern Allies. University of Hawaii Press, 2003. ISBN 978-0-8248-2522-5 . on page 70.
- ↑ a b Youxing Lin & Ronald Viane: Asplenium nidus Linnaeus . In: Flora of China, Vol. 2-3: 275-276. on-line
- ↑ Asplenium nidus L. In: Stuart Lindsay: Ferns of Thailand, Laos and Cambodia. on-line
- ↑ a b RE Holttum (1974): Asplenium Linn. sect. Thamnopteris Presl . In: Garden's Bulletin Singapore 27: 143-154.
- ^ Tropicos. [1]
- ^ Frans Verdoorn, AHG Alston: Manual of Pteridology. Springer Verlag, 2013. ISBN 978-94-017-6111-6 . on page 430.
- ↑ Tom M. Fayle, MD Farnon Ellwood, Edgar C. Turner, Jake L. Snaddon, Kalsum Mohd Yusah, William A. Foster (2008): Bird's nest ferns: islands of biodiversity in the rainforest canopy. In: Antenna 32: 34-37.
- ↑ Brett R. Scheffers, Ben L. Phillips, Luke P. Shoo (2014): Asplenium bird's nest ferns in rainforest canopies are climate-contingent refuges for frogs. In: Global Ecology and Conservation 2: 37-46. doi: 10.1016 / j.gecco.2014.06.004
- ^ Wim Giesen, Stephan Wulffraat, Max Zieren, Liesbeth Scholten: Mangrove Guidebook for southeast Asia. FAO Food and Agriculture Organization of the United Nations, Regional Office for Asia and the Pacific. Bangkok, 2006. Part 2: descriptions, Part A: Ferns. download
- ^ Asplenium nidus. Plants and Flowers, a comprehensive plants and flowers database.
- ^ Ian Bartholomew: Ferns on your plate. Taipei Times, January 9, 2016, accessed April 5, 2018 .
- ^ Daniel J. Ohlsen, Leon R. Perrie, Lara D. Shepherd, Patrick J. Brownsey, Michael J. Bayly (2014): Phylogeny of the fern family Aspleniaceae in Australasia and the south-western Pacific. In: Australian Systematic Botany 27: 355-371. doi: 10.1071 / SB14043
