Silberwurzen
| Silberwurzen | ||||||||||||
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White arum ( Dryas octopetala ) |
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| Scientific name | ||||||||||||
| Dryas | ||||||||||||
| L. |
The Silberwurzen ( Dryas ) are a genus of plants from the rose family (Rosaceae) with distribution in tundras and two alpine species in the northern hemisphere.
description
Silberwurzen are creeping, evergreen, woody dwarf shrubs. The closely spaced, oppositely arranged leaves are usually deeply incised at the edge, rarely with entire margins. Stipules are present.
The underarm, showy single flowers are long-stalked and hermaphrodite or reduced to one gender. The flower cup is cup or bowl-shaped. The seven to ten sepals are roof-tiled to flap-shaped , their number is always identical to that of the white, whitish or yellow petals . Stamens and pistils are numerous, the latter are ingrown on the bottom of the flower cup. The stylodes are terminal and long hairy. The tiny, linear scars are terminal and longitudinally furrowed.
The fruits are achenes that end in the not decaying, elongated and hairy stylodia. There is only one ovule . The seeds have a membranous surface. The number of chromosomes is 2n = 18.
distribution
The genus occurs in tundra and alpine regions of the northern hemisphere. While the white silver arum occurs in a circumpolar manner (also in Central Europe), Dryas drummondii is restricted to Northeast Asia and North America.
The fossil deposits (especially of Dryas octopetala L. ) from the glacial periods , which can be detected in sandy clay deposits, demonstrate the widespread distribution of Silberwurzen in the glacier-free north-western tundra vegetation of Europe , which gave its name to the Dryas flora of the Würm glacial period , especially the Younger Dryas period .
Systematics
The genus Dryas was established by Carl von Linné in 1753 . Together with the genera Cercocarpus , Chamaebatia and Purshia , it forms the subfamily Dryadoideae within the Rosaceae family .
Depending on the author, the genus Dryas contains two to about twenty species, eleven are currently widely recognized:
- Alaska silver arum ( Dryas alaskensis A.E.Porsild , Syn .: Dryas octopetala subsp. Alaskensis ( AEPorsild ) Hultén , Dryas octopetala f. Glabrata , Dryas punctata Juz. ): Alaska, Siberia, Central Asia
- Caucasus silver arum ( Dryas caucasica Juz. ): Caucasus
- Yellow Arum ( Dryas drummondii Richards. ): Canada, Northwestern United States: Alberta, British Columbia, Northwest Territories, Ontario, Quebec, Saskatchewan, Yukon, Alaska, Montana, Oregon.
- Great silver arum ( Dryas grandis Juz. )
- Hooker-Silberwurz ( Dryas hookeriana Juz. , Syn .: Dryas octopetala subsp. Hookeriana ( Juz. ) Hultén ): Western North America: Alberta, British Columbia, Northwest Territories, Alaska, Colorado, Idaho, Montana, Oregon, Utah, Washington, Wyoming.
- Incised silver arum ( Dryas incisa Juz. ): Siberia to Canada (Northwest Territories)
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Whole-edged Silberwurz ( Dryas integrifolia M.Vahl ): With the subspecies.
- Dryas integrifolia subsp. sylvatica Eastern Siberia to Northern Canada
- Dryas integrifolia subsp. integrifolia in southern Canada
- White silver arum ( Dryas octopetala L. ): Europe (to Central Asia?), Greenland
- Central Asian Silberwurz ( Dryas oxydonta Juz. ): Central Asia
- Sumnevicz silver arum ( Dryas sumneviczii Serg. )
- Sticky silver arum ( Dryas viscosa Juz. )
Web links
proof
- ↑ a b c d e C. Kalkman: Rosaceae. In: Klaus Kubitzki (Ed.): The Families and Genera of Vascular Plants - Volume VI - Flowering Plants - Dicotyledons - Celastrales, Oxalidales, Rosales, Cornales, Ericales , 2004, pp. 359-360, ISBN 978-3-540- 06512-8
- ↑ I. Skrede, PB Eidesen, RP Portela, C. Brochmann: Refugia, differentiation and postglacial migration in arctic-alpine Eurasia, exemplified by the mountain avens ( Dryas octopetala L. ) - Mol Ecol. 15 (7): 1827-1840, 2006.
- ↑ http://www.theplantlist.org/tpl1.1/search?q=Dryas , accessed November 30, 2016