Yew trees


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Yew trees
European yew tree (Taxus baccata), illustration

European yew tree ( Taxus baccata ), illustration

Systematics
Department : Vascular plants (tracheophyta)
Subdivision : Seed plants (Spermatophytina)
Class : Coniferopsida
Order : Conifers (Coniferales)
Family : Yew family (Taxaceae)
Genre : Yew trees
Scientific name
Taxus
L.

The yew trees ( Taxus ) form a genus of plants in the yew family (Taxaceae). The ten to eleven species are mainly found in the temperate areas of the northern hemisphere ; the European yew ( Taxus baccata ) is the only species native to Europe.

description

Female yew flowers with drops of pollination
The red seed coat envelops the seed like a cup, here on the European yew tree ( Taxus baccata )
This European yew was estimated to be around 1400 years old and is called the Hennersdorf yew . Until 1945 it was considered the oldest tree in Germany ; today it is considered the oldest tree in Poland

Vegetative characteristics

Yew species are evergreen shrubs or small to medium-sized trees . Young twigs initially have green to yellowish-green bark ; some bud scales can be seen at the bottom. Later the bark turns reddish-brown, a scaly, reddish-brown bark develops on older branches .

The needles are arranged in a spiral on the branch, but are parted so that they appear to be arranged in two rows. The straight, flexible needles can be straight or curved. They end in a small attached but not piercing point. The central vein protrudes on the top of the needles, on the bottom there are two light stripes with the stomata .

Generative characteristics

Yew species are usually dioeciously separated ( dioecious ): Male and female flowers are on separate plant specimens, occasionally they are single-sexed ( monoecious ). The male cones are spherical and yellowish. They have four to 16 sporophylls , each of which has two to nine sporangia.

The seeds ripen in the year of fertilization . Female plants produce red "fruits" in autumn that contain a single seed in the middle . The red, fleshy tissue surrounding the seed - the seed coat ( arillus ) - does not develop from the seed coat ( testa), but from the stem area of ​​the ovule ( funiculus ). The cup-shaped aril shows different shades of red depending on the species. In this case one does not speak of a fruit (in the botanical sense), but of a seed coat (arillus), since by definition there can only be fruits in flowering plants .

ecology

The pollen spreads via the wind ( anemophilia ). The seeds are mainly spread by birds, which eat the fleshy seed coat and later excrete the seeds again ( endochory ). Germination takes place epigeously , there are two cotyledons.

Deer and elk occasionally eat yew needles.

ingredients

Most species of yew, such as the European yew ( Taxus baccata ), contain very toxic ingredients such as taxin B. In particular, the Pacific yew ( Taxus brevifolia ) contains paclitaxel (Taxol), which is used to treat breast and ovarian cancer. Bark, needles and seeds are poisonous. However, the red seed coat does not contain any toxins. Cases of fatal poisoning by yew trees are known from humans, cattle and horses. The occurrence of ecdysterone has been described several times.

Occurrence

The yew species are mainly found in the temperate zone of the northern hemisphere. In the New World they still reach Mexico , Guatemala and El Salvador to the south . In Southeast Asia they are found in tropical mountain forests and cross the equator on Celebes . While they occur at lower altitudes in the north of their range, they reach altitudes of 3000 meters in the tropics.

The European yew ( Taxus baccata ) was originally widespread in Germany around the mountain regions. In 1568, Duke Albrecht informed the Imperial Council in Nuremberg that there were no more mature yew trees in all of Bavaria. The reason for this was that the English longbows were made from the wood of the yew trees . From Nuremberg , thousands of them were shipped to Antwerp as export hits in the past . The Paterzeller Eibenwald has been preserved as a small relic of the Eibenwald in the former monastery forest of Wessobrunn , as well as in the Eibenwald natural forest reserve in Gößweinstein . Other larger deposits are located in southern Lower Saxony near Bovenden north of Göttingen and in Thuringia in the Ibengarten near Dermbach in the Rhön , on Lengenberg west of Lutter (Eichsfeld) in the district of Heiligenstadt and in the nature reserve Dissau and Steinberg near Rudolstadt. The yew population on the Swiss Uetliberg is of European importance , where the city of Zurich even set up a yew nature trail.

Yew trees grow in the shrub layer of moist forests or form part of the crown layer.

Place names with the component “ib” refer to earlier yew trees, for example Unteribental or Unteriberg .

Systematics

Pacific yew ( Taxus brevifolia )
Japanese yew ( Taxus cuspidata )

The genus Taxus was established by Carl von Linné . The scientific generic name Taxus is etymologically derived from neo-Persian taχš for " crossbow , arrow" and ancient Greek τόξον for " arrow bow " (for which yew wood is particularly suitable) with (perhaps underlying both words) Scythian * taχša- connected as well as with the indefinable old Indian tree name takṣaka- .

The systematic delimitation of the species and varieties within the genus is difficult and the authors sometimes differ. Aljos Farjon distinguishes between the following types:

use

There are numerous crossings . The best-known cross is the hybrid yew ( Taxus × media Rehder ), a cross between Taxus baccata and Taxus cuspidata that originated in Massachusetts in 1900 . Their broad, columnar cultivated form 'Hicksii' is used relatively often in parks and gardens.

The wood of the European and Pacific yew, which is seldom commercially available, is relatively hard, very tough and elastic. It is mainly used for woodturning work, as well as veneer, the construction of musical instruments and, since ancient times, for the production of bows .

swell

  • Christopher J. Earle: Taxus Linnaeus 1753-Yew. In: The Gymnosperm Database. January 17, 2020, accessed on March 26, 2020 .
  • Richard W. Spjut: Overview of the Genus Taxus (Taxaceae): The Species, Their Classification, and Female Reproductive Morphology. 2010. online.

literature

  • Liguo Fu, Nan Li, Robert R. Mill: Taxaceae. In: Wu Zheng-yi, Peter H. Raven (Ed.): Flora of China. Volume 4: Cycadaceae through Fagaceae. Science Press and Missouri Botanical Garden Press, Beijing and St. Louis, 1999, ISBN 0-915279-70-3 . Taxus Linnaeus , p. 91 - online with the same text as the printed work.
  • Aljos Farjon: A Handbook of the World's Conifers . tape 2 . Brill, Leiden / Boston 2010, ISBN 978-90-04-17718-5 , pp. 969-985 .
  • Fred Hageneder et al .: The yew tree in a new light. A monograph of the genus Taxus with photos by Andy McGeeney. Verlag Neue Erde, Saarbrücken 2007, ISBN 978-3-89060-077-2 .
  • Petra Mensing et al .: Monograph of the Taxaceae Family. (= Scientific wood monographs. Volume 4). Verlag Gartenbild Hansmann, Rinteln 2005.

Individual evidence

  1. a b c d e f g h i j Liguo Fu, Nan Li, Robert R. Mill: Taxaceae. : In: Wu Zheng-yi, Peter H. Raven (Ed.): Flora of China. Volume 4: Cycadaceae through Fagaceae. Science Press and Missouri Botanical Garden Press, Beijing and St. Louis, 1999, ISBN 0-915279-70-3 . Taxus Linnaeus , p. 91 - online with the same text as the printed work.
  2. a b c d e f g h Matthew H. Hils: Taxaceae Gray. In: Flora of North America Editorial Committee (Ed.): Flora of North America North of Mexico. Volume 2: Pteridophytes and Gymnosperms. Oxford University Press, New York and Oxford, 1993, ISBN 0-19-508242-7 . Taxus - online with the same text as the printed work.
  3. a b c d e f g h i j k l Christopher J. Earle: Taxus Linnaeus 1753 - Yew. In: The Gymnosperm Database. January 17, 2020, accessed on March 26, 2020 .
  4. R. Hänsel, K. Keller, H. Rimpler, G. Schneider: Hagers Handbook of Pharmaceutical Practice . tape 6 . Springer Verlag, 1994 ( limited preview in the Google book search).
  5. ^ H. Hoffmeister, G. Heinrich, GB Staal, WJ van der Burg: On the occurrence of ecdysterone in yews. In: Naturwissenschaften , Volume 54, Issue 17, 1967, p. 471. PMID 5586986
  6. ^ NJ De Souza, El Ghisalberti, HH Rees, TW Goodwin: Studies on insect moulting hormones: biosynthesis of ponasterone A and ecdysterone from [2-14C] mevalonate in Taxus baccata. In: Biochem. J. , Volume 114, Issue 4, 1969, pp. 895-896. PMID 5343810
  7. br.de
  8. H.Meinhardt: yew deposits in Thuringia and problems of yew rejuvenation. (PDF; 607 kB) Bavarian State Institute for Forests and Forestry, 1994, accessed on March 21, 2017 .
  9. On the way to the yew trees on the Uetliberg. at www.stadt-zuerich.ch ; accessed on August 1, 2019.
  10. Alexandra Wehrle: District of Breisgau-Hochschwarzwald: Falkensteig: Eiben im Höllental: Rare tree is making a comeback. In: Badische Zeitung. April 22, 2015, accessed September 27, 2016 .
  11. ^ Taxus at Tropicos.org. Missouri Botanical Garden, St. Louis, accessed April 4, 2019.
  12. Helmut Genaust : Etymological Dictionary of Botanical Plant Names . 3. Edition. Birkhäuser , Basel / Boston / Berlin 1996, ISBN 3-7643-2390-6 , p.  631 f . ( taxícola. on p. 631 f in the Google book search).
  13. Alois Walde , Johann Baptist Hofmann : Latin Etymological Dictionary . 3. Edition. Carl Winter, Heidelberg 1954 ( taxus. P. 653. ).
  14. Systematics and identification key at worldbotanical.com .
  15. ^ David J. de Laubenfels: Coniferales. In: Flora Malesiana. Series I, Volume 10, Kluwer Academic, Dordrecht 1988, pp. 337-453.
  16. ^ Aljos Farjon: A Handbook of the World's Conifers. Volume 2, p. 970.
  17. Walter Erhardt , Erich Götz, Nils Bödeker, Siegmund Seybold: The great zander. Encyclopedia of Plant Names. Volume 2: Types and Varieties. Eugen Ulmer, Stuttgart (Hohenheim) 2008, ISBN 978-3-8001-5406-7 .
  18. Jürg Hassler-Schwarz: The yew (Taxus baccata L.): A description with special consideration of the canton of Graubünden. An attempt to describe the tree species with its physical and mythical characteristics ..., Publisher: Jürg Hassler-Schwarz, 1999.
  19. ^ Contributions to the yew / Bavarian State Institute for Forest and Forestry, Freising (Ed.): Reports from the Bavarian State Institute for Forest and Forestry. No. 10. Bavarian State Institute for Forests and Forestry. 1996.
  20. Michael Möller, Lian-Ming Gao, Robert R. Mill, Jie Liu, De-Quan Zhang, Ram Poudel, De-Zhu Li: A multidisciplinary approach reveals hidden taxonomic diversity in the morphologically challenging Taxus wallichiana complex. In: Taxon , Volume 62, Issue 6, 2013, pp. 1161–1177. doi : 10.12705 / 626.9
  21. Taxus cuspidata var. Nana in the IUCN Red List of Threatened Species 2019.1. Listed by: T. Katsuki, D. Luscombe, 2010. Retrieved May 4, 2019.
  22. Richard W. Spjut: Taxonomy and nomenclature of Taxus (Taxaceae). In: Journal of the Botanical Research Institute of Texas , Volume 1, Issue 1, 2007, p. 222. Full text PDF.
  23. Nick Gibbs: Encyclopedia Living with Wood . Fleurus Verlag, Cologne 2008, ISBN 978-3-89717-425-2 , p. 184-186 .

Web links

Commons : Eiben ( Taxus )  - Collection of images, videos and audio files