Bracken

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Bracken
Bracken (Pteridium aquilinum)

Bracken ( Pteridium aquilinum )

Systematics
Department : Vascular plants (tracheophyta)
Ferns
Class : True ferns (Polypodiopsida)
Order : Spotted ferns (Polypodiales)
Family : Dennstaedtiaceae
Genre : Bracken
Scientific name
Pteridium
Gleditsch ex Scop.

The bracken ( Pteridium ) are a worldwide common plant genus within the family Dennstaedtiaceae of ferns .

features

The bracken species are perennial herbaceous plants and reach heights of growth of 0.6 to 2 meters. They have a long, underground rhizome . Fertile and sterile fronds are designed more or less the same. They have a long stalk and are at a greater distance from each other on the rhizome. The fronds are triply pinnate and have nectaries on the lower feathers .

The sori are combined to form a line-like edge. They are covered by the bent edge of the leaf, creating a false veil .

Systematics and distribution

The genus Pteridium is placed in the Dennstaedtiaceae family. According to molecular studies based on the comparison of homologous DNA sequences, this position is quite well established

The system of the genre is still controversial to this day. In the Kew Plant List (based on the International Plant Names Index and Tropicos), which is often used as a reference , eleven species names are accepted as valid. The plants are morphologically variable, with individual morphological features correlating allometrically with one another. Problems also arise again and again because authors treat the taxonomy of the (worldwide) genus on the basis of its local or regional flora. The American botanist Rolla Milton Tryon Junior recognized in his revision of the genus from 1941 Pteridium aquilinum as the only species of the genus; numerous later editors followed him in it. An important step for the taxonomy of the genus was the work of Josua P. Der and colleagues who examined the phylogeny of the genus by comparing homologous DNA sequences of three sections of the plastid , other important contributions come from John A. Thomson. The European editors have largely followed this. According to these results, the genus can be genetically divided into two diploid lines that show roughly vicarious distribution, Pteridium aquilinum in the northern hemisphere and Pteridium esculentum in the southern hemisphere. In addition, there are (probably several) tetraploid allopolyploid lines, i.e. species that have emerged as fixed hybrids by means of genome duplication ( polyploidy ) from the crossing of these species.

The genus Pteridium is distributed almost worldwide. There are about eleven species of Pteridium :

  • Bracken ( Pteridium aquilinum (L.) Kuhn ): Type species of the genus: There are numerous subspecies.
  • Pteridium arachnoideum (Kaulf.) Maxon : According to Thomson 2012, it is a subspecies of Pteridium esculentum
  • Pteridium caudatum (L.) Maxon : Central and South America. Hybridogenic species, allotetraploid hybrid from Pteridium aquilinum and Pteridium esculentum
  • Pteridium centrali-africanum (Hieron.) Alston : After the revision of Thomson et al. it is a subspecies of Pteridium aquilinum
  • Pteridium esculentum (G. Forst.) Cockayne : New Zealand, Australia, South Asia, Central and South America.
  • Pteridium falcatum Ching ex SHWu : China. Dubious species, never found againafter the first description , even when searching at the type locality . Presumably synonymous with Pteridium aquilinum subsp. japonicum
  • Pteridium feei (W.Schaffn. Ex Fée) Faull. : Central Mexico. Rarely found, probably synonymous with Pteridium aquilinum
  • Pteridium linear Ching ex SHWu : China. Dubious species, never found again after the first description, even when searching at the type locality. Presumably synonymous with Pteridium aquilinum subsp. wightianum
  • Pteridium revolutum (flower) Nakai : Southeast Asia. Synonym for Pteridium aquilinum subsp. wightianum (J.Agardh) WCShieh
  • Pteridium tauricum V.I. Krecz. : Caucasus. Differentiation from Pteridium aquilinum unclear. Synonym of Pteridium aquilinum according to numerous authors
  • Pteridium yunnanense Ching & SHWu : China. Dubious species, never found again after the first description, even when searching at the type locality. Presumably synonymous with Pteridium aquilinum subsp. wightianum

swell

  • Siegmund Seybold (Ed.): Schmeil-Fitschen interactive . CD-ROM, version 1.1. Quelle & Meyer, Wiebelsheim 2002, ISBN 3-494-01327-6 .

Individual evidence

  1. ^ Alan R. Smith, Kathleen M. Pryer, Eric Schuettpelz, Petra Korall, Harald Schneider, Paul G. Wolf (2006): A classification for extant ferns. Taxon 55 (3): 705-731
  2. ↑ Kathleen M. Pryer, Eric Schuettpelz, Paul G. Wolf, Harald Schneider, Alan R. Smith, Raymond Cranfill (2004): Phylogeny and evolution of ferns (monilophytes) with a focus on the early leptosporangiate divergences. American Journal of Botany 91 (10): 1582-1598.
  3. ↑ Eric Schuettpelz, Petra Korall, Kathleen M. Pryer (2006): Plastid atpA data provide improved support for deep relationships among ferns. Taxon 55 (4): 897-906.
  4. ^ Pteridium in The Plant List (2013). Version 1.1. Published on the Internet , accessed December 1, 2014
  5. ^ Pteridium at Tropicos, Tropicos.org, Missouri Botanical Garden
  6. ^ RM Tryon, Jr. (1941): A revision of the genus Pteridium. Contributions from the Gray Herbarium of Harvard University No. 134: 1-31, 37-67.
  7. ↑ Joshua P. Der, John A. Thomson, Jeran K. Stratford, Paul G. Wolf (2009): Global chloroplast phylogeny and biogeography of bracken (Pteridium; Dennstaedtiaceae). American Journal of Botany 96 (5): 1041-1049.
  8. ↑ a b cf. RH Marrs & AS Watt (2006): Biological Flora of the British Isles: Pteridium aquilinum (L.) Kuhn. Journal of Ecology 94: 1272-1321.
  9. ^ John A. Thomson (2004): Towards a taxonomic revision of Pteridium (Dennstaedtiaceae). Telopea 10 (4): 793-803.
  10. ^ A b John A. Thomson (2012): Taxonomic Status of Diploid Southern Hemisphere Brackens (Pteridium: Dennstaedtiaceae). Telopea Volume 14: 43-48.
  11. ^ A b J. A. Thomson, AC Chikuni, CS McMaster (2005): The taxonomic status and relationships of bracken ferns (Pteridium: Dennstaedtiaceae) from sub-Saharan Africa. Botanical Journal of the Linnean Society 148: 311-321. doi : 10.1111 / j.1095-8339.2005.00413.x
  12. ↑ a b c Shiliang Zhou, Wenpan Dong, Xiaoqing Chen, Xianchun Zhang, Jun Wen, Harald Schneider (2014): How many species of bracken (Pteridium) are there? Assessing the Chinese brackens using molecular evidence. Taxon 63 (3): 509-521.
  13. ^ John A. Thomson (2008): Morphotype and conflicting taxonomies in Pteridium (Dennstaedtiaceae: Pteridophyta). Fern (Graz) 18 (3): 101-109.

Web links

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