Taxaceae

Yew (Taxus baccata ), illustration

The Yews ( Taxaceae ) form a family of plants in the order of conifers ( Coniferales ). Some species are used worldwide as ornamental plants in parks and gardens.

  • 5.1 Notes and references

The best-known type

The best-known representative of the family in Central Europe is the European yew ( Taxus baccata ), which is also planted in parks or gardens. The whole plant and its seeds are very toxic, the aril remains toxic. The poison is called Taxin, it contains inter alia the diterpene taxol. After eating several " berries ", a doctor should be consulted.

Description

Vegetative characteristics

There are evergreen trees and shrubs. They are usually not resinous and not smell aromatic. The bark is scaly or fibrous. The leaves are arranged on Amentotaxus up, alternate or spiral, but often appear as two lines on the branches and remain there for several years. The needle-like leaves are flattened. The seedlings have two seed leaves ( cotyledons ).

Generative features

The types of Taxaceae are getrenntgeschlechtig: monoecious ( monoecious ), but mostly dioecious ( dioecious ). The male pin-shaped flowers are axillary individually or several together on one-year branches; they are spherical to ovoid. The sporophylls have two to twelve microsporangia ( pollen sacs ). The spherical pollen are not winged. Spreading the pollen carried by the wind. The axillary standing on one-year branches, female cones are reduced to a single peg scale that has one or two ovules.

The pin only a seed is formed. The seed has a hard seed coat and is the maturity time of a seed coat ( aril ) ( a fleshy shell of a berry looks somewhat similar ) partially or completely ( Torreya ) surrounded. The aril may be intensely colored and be juicy, fleshy or leathery. From the color and taste of the aril animals, above all birds ( Ornithochorie ) are attracted. The aril is usually eaten with its hidden seed and the seed is then excreted undigested.

Systematics and distribution

The genera of the family of Yews are mainly found in the northern hemisphere. The range extends south to the Philippines and Mexico, and with the kind Austrotaxus spicata in New Caledonia on the southern hemisphere. In China, four genera occur with eleven species.

The Taxaceae family includes five genera with 17-20 species. There are two tribes; among other things, due to the morphology of the aril:

  • Tribus Torreyeae: With completely or almost completely by aril coated seeds: Amentotaxus pilgrims: With five species in China, India, Vietnam and Taiwan.
  • Nut yew ( Torreya Arnott ): With six species in western North America and Southeast Asia.
  • Austrotaxus Compton: Is a monotypic genus, there is only one way: Austrotaxus spicata Compton: It is native to New Caledonia.
  • Pseudotaxus chienii ( WCCheng ) WCCheng: It is located in the south of China.

The separation of Austrotaxus ( Austrotaxaceae Nakai ex Takht. & Reveal ) Amentotaxus ( Amentotaxaceae Kudo & Yamam. ) And Torreya ( Torreyaceae Nakai ) as their own families has not prevailed. The scope of the two families Yews and head Yews ( Cephalotaxaceae ) is discussed. There are also authors in which both families contain three genera. Also, a merger of the two families with then six genera in the Taxaceae sl was up for discussion. However, a phylogenetic study confirms the herein described internal classification of Yews and the status of the head of yew, illustrated by the following cladogram:

Taxus

Pseudotaxus

Austrotaxus

Torreya

Amentotaxus

Cephalotaxus

Pictures

Cones of Taxus cuspidata.

Habit of Taxus chinensis.

Swell

  • Christopher J. Earle. Family Information from The Gymnosperm Database, 2009 (English )
  • Matthew H. Hils: Taxaceae in the Flora of North America, Volume 2: Online.
  • Liguo Fu, Nan Li & Robert R. Mill: Taxaceae in the Flora of China, Volume 4, page 89: Online.
  • Andreas Bresinsky, Ch grains, JW Kadereit, G. Neuhaus, U. Sonnewald. Strasburger - Textbook of Botany, 36th edition, Spektrum Akademischer Verlag, Heidelberg 2008, ISBN 978-3-8274-1455-7, pp. 840 - 841
  • Bulk (ed.) et. al: . Encyclopedia of woody plants. Manual and Atlas of Dendrology, Landsberg am Lech 1994 ( base; ISBN 3-609-72030-1 ) / supplement episodes 1995 ff
Pinophyta Amentotaxus formosana Digital Object Identifier
298198
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