Small algae fern

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Small algae fern
Azolla caroliniana1.jpg

Small algae fern ( Azolla mexicana )

Systematics
Ferns
Class : True ferns (Polypodiopsida)
Order : Floating ferns (Salviniales)
Family : Swimming fern family (Salviniaceae)
Genre : Algae ferns ( Azolla )
Type : Small algae fern
Scientific name
Azolla mexicana
C. Presl

The Small Azolla ( Azolla mexicana ) of aquarists also Feenmoos called, is a plant of the genus of Azolla within the family of salviniaceae (Salviniaceae). The species is taxonomically controversial and is used by different taxonomists in different delimitations and under different scientific names. Her home is North and Central America . In Central Europe , the species is considered to be an inconsistent neophyte .

features

The small algae fern is an aquatic plant floating on the surface of the water with a short, completely leafy rhizome and simple, unbranched roots . The leaves are green or reddish in color. The rosette individual plants have a diameter of 1 to 1.5 centimeters. On the upper side, two rows of small, overlapping, scale-like leaves are visible, which sit alternately on the forked (dichotomously) branched rungs. On closer observation it can be seen that the leaves are divided into two parts, each consisting of an upper lobe floating on the surface of the water and a submerged, rarely also floating lower lobe. The top of the upper lobes is densely covered with papillary hair and is therefore not wettable.

As is typical for the whole family group, the spores are formed in rounded organs surrounded by a sterile shell, called sporocarpies, which are in pairs in the leaf axils. The macrospores (“female” spores of the heterosporous fern), which are provided with a float, sit individually in the sporangia. The numerous “male” microspores are released in rounded packages called massulae. Numerous spores are encased in a foam-like perispore that has numerous small barbs on the outside, which are called glochidia. The species remains mostly sterile and reproduces vegetatively, sporangia are usually only formed in very dense stands towards the end of the growing season.

The following vegetative distinguishing features from the large algae fern ( Azolla filiculoides ), which is much more common in Europe, are given: floating leaf upper lobe pointed, not rounded, with a narrow (not wide) skin edge. The species of the genus Azolla , however, are variable and diverse and cannot be reliably determined on the basis of these characteristics. Important determinants for an exact address are: Hair on the upper side of the leaf (papillae) consisting of two cells, glochidia with at least two transverse walls (septa) chambered, surface of the macrospores uneven, with numerous pit-like depressions. The taxonomic value of this and a number of other features is disputed between different investigators, so that an exact determination is currently only possible for specialists. One possible delimitation, which is not accepted by all botanists, can be found in the flora of North America.

Taxonomy

The species belongs within the genus Azolla in a group that is usually taken as the Azolla section ; this was recognized as a monophyletic unit in both morphological and phylogenomic studies . However, the number and delimitation of the species within the section are controversial, and the correct name of the different plant species is also disputed between different taxonomists, so that different units are referred to with the same name or distinguishable taxa with different names between different authors. Because of this confusion, it is difficult to say which clan is meant in the case of published information relating to Azolla species. Different editors differentiated within the Azolla section , in addition to the type Azolla filiculoides, among others the species Azolla caroliniana Willd. , Azolla cristata Kaulf. , Azolla microphylla Kaulf. and Azolla mexicana Presl. In an influential revision based on morphological features, Evrard and van Hove came to the conclusion in 2004 that only two species of the section can be distinguished in North America (the botanist Georg Heinrich Mettenius had already suggested this in 1867). The second species, which would include all names with the exception of A. filiculoides , should, in their opinion, be Azolla cristata Kaulf for reasons of priority . (syn Azolla caroliniana auct. non Willd.). A big problem is, among other things, that the type specimen of Azolla caroliana is a non-spore-forming plant, which means that a determination and comparison with clans later named under this name are uncertain. A genetic study by Jill Reid and colleagues differentiated three species, a combined morphological and genetic study by Ana Pereira and colleagues again four types. In a further genetic investigation, Azolla mexicana and Azolla microphylla were found to be paraphyletic against each other, so they probably form only one species. The name Azolla cristata was also used for (Kashmir) plants introduced in northern India, the Christopher Roy Fraser-Jenkins as a new subspecies of Azolla filiculoides , in which many botanists have followed him. For the algae ferns of North America, which do not belong to Azolla filiculoides , various names are still in use, including Azolla mexicana and Azolla caroliniana , Azolla cristata and Azolla microphylla . There is genetic evidence that what goes under the name Azolla caroliniana (auct. Non Willd.) Is a clan of hybrid origin, which has also been suspected based on morphological features.

In Europe, the second species introduced from America, which is called the small algae fern to distinguish it from the large algae fern, is traditionally usually called Azolla caroliniana . In recent times, the name Azolla mexicana is mostly used here . In the standard list of fern and flowering plants none of these species is currently recognized for Germany.

distribution

The small algae fern, Azolla mexicana, is distributed in several separate (disjoint) areas in North and Central America, probably also in northern South America . In North America the occurrences are mainly in the west (including the Great Plains ), in Arizona, Arkansas, California, Colorado, Illinois, Iowa, Kansas, Minnesota, Missouri, Nebraska, Nevada, New Mexico, Oklahoma, Oregon, Texas, Utah , Washington, and Wisconsin, with the northern limit of distribution in British Columbia (Canada). In eastern and south-eastern North America the occurrence of Azolla caroliniana s closes . st. on.

The species has been introduced from its natural range to numerous regions of the world with similar climates. It occurs quite often in South Africa . In the case of the European occurrence of algae ferns, it is difficult to assign them to one of the species due to the taxonomic problems; older information without critical examination is often generally rejected as implausible. This means that there is a risk that some occurrences in southern and south-eastern Europe that are listed as large algae ferns are actually this species.

While the large algae fern is now widespread in Germany and has been added to the black list of invasive species of the Federal Agency for Nature Conservation because of its undesirable spread , the small algae fern has only been given a few times, previously always inconsistent.

Ecology and location

The species forms floating leaf covers on stagnant or very slowly flowing waters, in Europe mostly together with duckweed species ( Lemna spp.). Like the great algae fern, it prefers warm, nutrient-rich waters. Both species often appear together, together with the neophytic Lemna turionifera . Due to the higher heat requirement and the lower frost hardness, the species is ecologically more demanding towards the north.

Like the great algae fern, the species hosts the herbivorous weevil Stenopelmus rufinasus .

Individual evidence

  1. ^ Rudolf Schubert, Walter Vent: Exkursionsflora von Deutschland (founded by Werner Rothmaler). Volume 4 (critical volume). Volk und Wissen Verlag, Berlin 1990, p. 96.
  2. ↑ Klaus van de Weyer, Carsten Schmidt: Identification key for the aquatic macrophytes (vascular plants, candelabrum algae and mosses) in Germany. Version 1.1, 05/20/2007. published by the Ministry for Rural Development, Environment and Consumer Protection of the State of Brandenburg, Potsdam 2007.
  3. ^ A b Thomas A. Lumpkin: Azolla. In: Flora of North America online. Vol. 2.
  4. ↑ Azolla. in Tropicos.org. Missouri Botanical Garden. accessed on October 4, 2017.
  5. ↑ C. Evrard, C. Van Hove: Taxonomy of the American Azolla Species (Azollaceae): A Critical Review. In: Systematics and Geography of Plants. 74 (2), 2004, pp. 301-318. JSTOR: 3668500
  6. ^ Jill D. Reid, Gregory M. Plunkett, Gerald A. Peters, Phylogenetic Relationships in the Heterosporous Fern Genus Azolla (Azollaceae) Based on DNA Sequence Data from Three Noncoding Regions. In: International Journal of Plant Sciences. 67 (3), 2006, pp. 529-538. doi: 10.1086 / 501071
  7. ↑ Ana L. Pereira, Madalena Martins, M. Margarida Oliveira, Francisco Carrapiço: Morphological and genetic diversity of the family Azollaceae inferred from vegetative characters and RAPD markers. In: Plant Systematics and Evolution. 297 (3-4), 2011, pp. 213-226. doi: 10.1007 / s00606-011-0509-0
  8. ↑ Jordan S. Metzgar, Harald Schneider, Kathleen M. Pryer: Phylogeny and divergence time estimates for the fern genus Azolla (Salviniaceae). In: International Journal of Plant Sciences. 168 (7), 2007, pp. 1045-1053.
  9. ↑ Burhan Ahad, Zafar A. Reshi, Aijaz H. Ganaie: Azolla cristata in the Kashmir Himalaya. In: American Fern Journal. 102 (3), 2012, pp. 224-227.
  10. ↑ Christopher Roy Fraser-Jenkins: Rare and Threatened Pteridophytes of Asia 2. Endangered Species of India - the Higher IUCN Categories. In: Bulletin of the National Museum of Nature and Science. Series B, Botany, 38 (4), 2012, pp. 153-181.
  11. ↑ Karina Magdalena Grajales-Tam: Azollaceae. Flora del Bajio y de regiones adyacentes. In: Fascículo. 185, 2014, pp. 1-9.
  12. ↑ James H. Peck: New and noteworthy additions to the Arkansas fern flora. In: Phytoneuron. 30, 2011, pp. 1-33.
  13. ^ J. Monterrosa, AK Monro: An annotated checklist of the Monilophytes (ferns) and Lycophytes of El Salvador. In: Fern Gazette. 18 (4), 2008, pp. 120-215.
  14. ↑ Paul T. Madeira, Ted D. Center, Julie A. Coetzee, Robert W. Pemberton, Matthew F. Purcell, Martin P. Hill: Identity and origins of introduced and native Azolla species in Florida. In: Aquatic Botany. 111, 2013, pp. 9-15. doi: 10.1016 / j.aquabot.2013.07.009
  15. ^ DG Dunham, K. Fowler: Taxonomy and species recognition in Azolla Lam. In: Azolla Utilization. In: Proceedings of the Workshop on AzoIla Use, Fuzhou, Fujian, China, March 31-April 5, 1985. International Rice Research Institute, Manila, Philippines 1987, ISBN 971-10-4179-0 .
  16. ↑ Azolla mexicana C. Presl, Small algae fern. In: FloraWeb - data and information on wild plants and vegetation in Germany. accessed on October 4, 2017.
  17. ↑ G. Phillippi: Azollaceae. In: Oskar Sebald, Siegmund Seybold, Georg Philippi (eds.): The fern and flowering plants of Baden-Württemberg. Volume 1: General Part, Special Part (Pteridophyta, Spermatophyta): Lycopodiaceae to Plumbaginaceae. Eugen Ulmer, Stuttgart (Hohenheim) 1990, ISBN 3-8001-3309-1 .
  18. ↑ Azolla. Standard list of fern and flowering plants, electronic version, accessed October 4, 2017.
  19. ^ British Columbia Ministry of Environment: Recovery plan for the Mexican mosquito fern (Azolla mexicana) in British Columbia. BC Ministry of Environment, Victoria, BC, 2016. (25 pages)
  20. ↑ a b given under the synonymous name Azolla cristata : PT Madeira, MP Hill, FA Dray Jr., JA Coetzee, ID Paterson, PW Tipping: Molecular identification of Azolla invasions in Africa: The Azolla specialist, Stenopelmus rufinasus proves to be an excellent taxonomist. In: South African Journal of Botany. 105, 2016, pp. 299-305. doi: 10.1016 / j.sajb.2016.03.007
  21. ↑ Richard V. Lansdown, Paulina Anastasiu, Zoltán Barina, Ioannis Bazos, Halil Çakan, Danka Caković, Pinelopi Delipetrou, Vlado Matevski, Božena Mitić, Eszter Ruprecht, Gordana Tomović, Anita Tosheva, Gergely Király: Review of Alien Freshwater. Vascular Plants -east Europe. In: M. Rat, T. Trichkova, R. Scalera, R. Tomov, A. Uludag (Eds.): Esenias Report 2015 - State of the Art of Invasive Alien Species in South-Eastern Europe. University of Novi Sad Faculty of Sciences, Department of Biology and Ecology, Novi Sad, Serbia East and South European Network for Invasive Alien Species, Sofia, Bulgaria, pp. 138–154.
  22. ↑ Andreas Hussner, Klaus van de Weyer, Elisabeth Maria Gross, Sabine Hilt: An overview of the aquatic neophytes in Germany - establishment, effects and management perspectives. In: Handbook Applied Limnology: Basics - Water pollution - Restoration - Aquatic ecotoxicology - Assessment - Water protection. 1, 2014, pp. 1–28. doi: 10.1002 / 9783527678488.hbal2010004 (open access)
  23. ↑ Peter Wolff, Herbert Diekjobst, Arno Schwarzer: On the sociology and ecology of Lemna minuta H., B. & K. in Central Europe. In: Tuexenia. 14, 1994, pp. 343-380.

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