White arum

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White arum
Silverwort (Dryas octopetala)

Silverwort ( Dryas octopetala )

Systematics
Rosids
Eurosiden I
Order : Rose-like (rosales)
Family : Rose family (Rosaceae)
Genre : Silberwurzen ( Dryas )
Type : White arum
Scientific name
Dryas octopetala
L.

The white silver arum ( Dryas octopetala ) belongs to the genus Dryas in the rose family (Rosaceae). The silver arum is an arctic-alpine species of the northern hemisphere that is circumpolar. After macrofossil remnants of the white silver root appeared in peat deposits in Sweden and Denmark in the second half of the 19th century , these so-called "Dryas peat" formed the first evidence of extreme climatic changes that occurred several millennia after the ice retreat in the last Glacial maximum level of the Vistula / Würme Ice Age ( LGM ) and gave the name to the geological epoch of the Dryas period . It was evidence of a recent sudden global climate deterioration just before the Holocene warm phase. The silver arum is an exemplary climate indicator of arctic conditions and glacial periods. Where it occurs recently in the middle latitudes, it is also a glacial relic in any case . It is one of the landmarks of the arctic-alpine flora of the high mountains of Europe and the Alps, and ecologically the most distinctive type of espalier bush .

Origin of name

The genus was called Chamaedrys in the 16th century , which means dwarf oak (from the Greek chamei = dwarf and drys = oak). Carl von Linné gave the genus the name Dryas in the 18th century with the botanical addition octopetala because of the mostly eight white petals. This is an exception in the family where five-fold flowers are otherwise common.

description

Vegetative characteristics

Evergreen, heavily branched espalier shrub with prostrate long shoots and only 2–10 cm long, erect short shoots, occasionally with roots, reddish-brown, mostly hairy, partly covered with remnants of leaves, which are finally shed with the ring bark. Foliage leaves on the creeping shoots approximately two-lined, on the upright standing all around, evergreen, leathery coarse. Petiole about 1–2 cm long, hairy, blade dark green on top with a deep network of veins, mostly glabrous, below thickly white tomentose with protruding main and side nerves, usually narrowly folded down on the edge, mostly oblique, rounded to somewhat heart-shaped base oblong to elliptical indicated (wrongly) ovate, rounded or blunt at the front, with 4–8 (–10) mostly blunt to 2–3 mm long serrations, 5–30 (–40) mm long, 5–15 (–20) mm wide. Stipules mostly dry-skinned, hairy, very narrow, linear-triangular, about two-thirds of their length fused with the petiole, the loose section about 4–7 mm long and 1–1.5 mm wide.

It forms a strong taproot. The creeping branches and twigs can reach a length of up to one meter.

Generative characteristics

The seeds of the white silver arum are spread by the wind

The hermaphroditic or more or less severe atrophy of the stamens or carpels polygamous, radial symmetry flowers are single, on terminal, upright, usually about 5–10 cm high, (felty) dense-haired and especially in the upper part glandular-haired stems, which turn to the Extend the fruiting time a little, with the petals spread out about 2.5–4 cm wide. Calyx lobes mostly (7–) 8 (–9), broadly linear- lanceolate, slightly pointed, 6–11 mm long, 2–3.5 mm wide, brownish tomentose and glandular on the outside, glabrous on the inside. Petals the same number as the sepals, pure white, obovate, 10–18 mm long, 5–12 mm wide, glabrous, falling soon after flowering. Stamens numerous, glabrous, 7–11 mm long, not as high as or towering over the style. Carpel numerous, close-haired, with a terminal stylus that is initially twisted into a screw and rolled up at the tip, which elongates to 2–3 cm when the fruit is ripe and develops feathery-white, silver-shimmering hairs. Fruit base slightly arched, hairy, does not stretch when the fruit is ripe.

Flowering period: June to July. At low altitudes as early as May. In the high mountains and in the Arctic mid-June to early August. The fruits spread through hairy appendages with the help of the wind ( wind spread ). The fruit ripens from July.

Chromosome number

The number of chromosomes is 2n = 18 or 36.

distribution

White arum on Monte Piana , Italy
Close-up of a white silver arum in the Ötschergräben , Lower Austria

Recent

The species is distributed arctic-alpine. In addition to the Alps and other mountain ranges of Central and Southern Europe, the area includes the Arctic region, Northern Europe, Siberia, Eastern Asia and North America. In northern Sweden, silver arum, together with mosses and lichens, forms the main vegetation on the tundra . In the south, the distribution area of ​​the species extends to northern Spain, central Italy, the Rhodope Mountains in southern Bulgaria, as well as in Greece on the Macedonian-Greek border (Tzena, Voras mountains) and the Bulgarian-Greek border (Orvilos, Falakron in the Rhodope Mountains).

Dwarf shrub heaths of the arctic tundras, moraine rubble , rock corridors, mats and calcareous rubble corridors above the tree line are preferred as locations . In the Alps, this type of plant can be found between 1200 and 2500 meters. In Northern Europe, acidic soils are preferred. It is a character species of the Carici-Kobresietea class, but also occurs in societies of the Thlaspietea rotundifolii or the Seslerion class.

Dryas octopetala and more often their hybrids with the North American species Dryas drummondii , Dryas × suendermannii Kellerer ex Sünd. , are occasionally used as ornamental plants in rock gardens .

quaternary

Fossils from Dryas are key species of the Quaternary flora, the fossil data on late glacial distribution clearly represent ice age climatic changes. From the contrast between today's and late glacial distribution during the Last Glacial Maximum (LGM), conclusions about the climate and extent of periglacial tundras in Europe can be reconstructed. The late glacial territory of the white silver arum included the flatlands of Eastern Ireland, Great Britain south of Scotland, Brittany, the Benelux countries, Central and Eastern Europe as well as the northern Pannonian and practically the entire Po valley. From this compact and coherent distribution area, the populations migrated in the warm phases and interstadial to more northerly or higher-lying locations in the high mountains. These climatically induced migratory movements can be found analogously in many other arctic-alpine species which are known as arctic-alpine disjunction .

During the Younger Dryas Period (approx. 10,730–9,700 BC) the species was widespread throughout Europe, which is evident from the pollen analyzes from this period. The period at the end of the Pleistocene was named after this plant.

ecology

The plant is extremely frugal if it gets enough light. Since the plant is metabolically active for only a few weeks a year, it can reach an old age of up to 100 years.

During the short arctic or high mountain summer, the flowers follow the sun like a parabolic antenna. As a heat collector, they represent an attractive landing place for insects. The shoot and flower buds are created in the previous vegetation period.

The White Mountain Avens has root nodules , with actinomycetes of the genus Frankia air nitrogen bind. In addition, they enter into a symbiosis with ecto mycorrhizal fungi , such as B. the strong-smelling chanterelle , Tomentella sp., Dryadirhiza fulgens and Cenococcum geophilum .

Systematics

Dryas integrifolia

Depending on the view, the genus includes two to three species ( Dryas drummondii , Dryas octopetala and Dryas integrifolia ).

The pale yellow blooming species Dryas drummondii and the white blooming Dryas integrifolia colonize the mountains of North America, whereby Dryas integrifolia is also regarded as a variety of Dryas octopetala ( Dryas octopetala var. Integrifolia ).

Common names

The other German-language trivial names exist or existed for the white silver arum: Alpengamänderlin, Berggamanderlin, white Gathau ( Pinzgau near Fusch ), Hirtzwurz, Kateinl (Pinzgau).

Others

The white silver arum is often well preserved in fossil form . The blossoms, fruits and pollen have withstood thousands of years in ice-age clay deposits. With the end of the Ice Age, the plant species was widespread across Germany (evidence from pollen analyzes ). After this type of plant, this period was called the Dryas period (silver root period).

natural reserve

This plant species is protected by law in certain areas. The silver arum is the symbol of the Swedish province of Lapland and has been Iceland's national flower since 2004 .

literature

  • Xaver Finkenzeller: Alpenblumen , Munich 2003, ISBN 3-576-11482-3
  • Kremer: shrub trees . Niedernhausen, 2002. ISBN 3-576-11478-5
  • Manfred A. Fischer , Wolfgang Adler, Karl Oswald: Excursion flora for Austria, Liechtenstein and South Tyrol. 2nd, improved and enlarged edition. State of Upper Austria, Biology Center of the Upper Austrian State Museums, Linz 2005, ISBN 3-85474-140-5 .
  • Ruprecht Düll , Herfried Kutzelnigg : Pocket dictionary of plants in Germany. A botanical-ecological excursion companion to the most important species. 6th, completely revised edition. Quelle & Meyer, Wiebelsheim 2005, ISBN 3-494-01397-7 .

Web links

Commons : White Silberwurz ( Dryas octopetala )  - Album with pictures, videos and audio files
Wiktionary: Silberwurz  - explanations of meanings, word origins, synonyms, translations

swell

  1. ^ Hilary H. Birks 2008: The Late-Quarternary history of arctic and alpine plants . In: Richard J. Abbott (Ed.) 2008: History, evolution and future of arctic and alpine flora . Plant Ecology & Diversity, Special Issue, Vol. 1/2, November 2008, 135-146. ISSN 1755-0874 here p. 137
  2. ^ Heinrich E. Weber 1995: Dryas. In: Hans J. Conert, Eckehart j. Jäger, Joachim W. Kadereit, Wolfram Schultze-Motel, Gerhard Wagenitz, Heinrich E. Weber (eds.) Gustav Hegi - Illustrated Flora of Central Europe, Volume 4: Angiospermae - Dicotyledones 2 (2), 3rd, 641–648, completely Revised and expanded edition, Weißdorn-Verlag, Jena 1995. ISBN 3-8263-3016-1 Here p. 642
  3. ^ Heinrich E. Weber 1995: p. 642
  4. a b Erich Oberdorfer : Plant-sociological excursion flora for Germany and neighboring areas . 8th edition. Verlag Eugen Ulmer, Stuttgart 2001, ISBN 3-8001-3131-5 . Page 545.
  5. ^ Arne Strid, Kit Tan 1986: Mountain Flora of Greece . Cambridge University Press, Vol. 1. ISBN 0521257379 Here p. 401
  6. Hilary H. Birks 2008: p. 138
  7. Hilary H. Birks 2008: p. 139
  8. Harrington TJ, Mitchell DT., 2005. Ectomycorrhizas associated with a relict population of Dryas octopetala in the Burren, western Ireland II. Composition, structure and temporal variation in the ectomycorrhizal community. Mycorrhiza 15: 435-445.
  9. ^ Robert Zander : Zander. Concise dictionary of plant names. Edited by Walter Erhardt , Erich Götz, Nils Bödeker, Siegmund Seybold . 17th edition. Eugen Ulmer, Stuttgart 2002, ISBN 3-8001-3573-6 .
  10. ^ Georg August Pritzel , Carl Jessen : The German folk names of plants. New contribution to the German linguistic treasure. Philipp Cohen, Hannover 1882, page 138. ( online ).