Canadian fleabane

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Canadian fleabane
Canadian fleabane (Conyza canadensis)

Canadian fleabane ( Conyza canadensis )

Systematics
Order : Astern-like (Asterales)
Family : Daisy family (Asteraceae)
Subfamily : Asteroideae
Tribe : Astereae
Genre : Fleabane Herbs ( Conyza )
Type : Canadian fleabane
Scientific name
Conyza canadensis
( L. ) Cronquist

The Canadian fleabane ( Conyza canadensis ), also cats tail and White Dürr Wurz called, is a species of the family of the daisy family (Asteraceae). It is also often listed under the scientific name Erigeron canadensis of the genus Erigeron .

description

illustration
Rispied whole inflorescence
Flower heads
Achenes with pappus

The Canadian fleabane is a herbaceous plant that is one to two years old and that is slender and upright and reaches a height of 30 to 100 centimeters, and even more in favorable locations. Its roots are over 1 m deep. The stem is only branched in the area of ​​the inflorescence.

The closely spaced, alternate leaves are linear to linear-lanceolate with a maximum width of 1 centimeter. The lower, rosette-like leaves are a little wider than the upper, narrow oval or narrow spatula-shaped and often roughly toothed. Stems and leaves are loosely shaggy hairy.

In a paniculate entire inflorescence there are usually very numerous flower heads (over 100 to a few thousand). The flower heads are about 3 to 4 mm long. The hairless bracts stand in two to three indistinct rows, the inner ones are slightly longer than the outer ones.

Each flower head contains 50 to 65 flowers . The hermaphroditic florets are yellowish to greenish, the 25 to 45 marginal ray florets whitish or greenish, from time to time with a purple cast. The ray-florets are only a few millimeters long, more or less upright and protrude only about 1 mm beyond the envelope. The flowering period in Europe is from July to October.

When ripe, a dirty white pappus of simple and toothed hairs 2 to 3 mm long forms on the 1 mm long achenes .

The number of chromosomes is 2n = 18.

ecology

Self-pollination probably takes place in the flowers. It forms abundant fruits, which spread with the wind as an umbrella flyer . Around 25,000, or even 250,000 fruits in the case of stately specimens, were counted. The Canadian fleabane is a pioneer plant with roots up to one meter deep. It occurs optimally when re-colonizing fallow land, especially in the second and third year.

Varieties of Conyza canadensis were the first so-called superweeds to be created and proven in the USA as a result of extreme selection pressure from glyphosate . It is believed that they appeared in connection with the culture of glyphosate-resistant (GR) soybeans.

Occurrence

Canadian fleabane is native to the United States and southern Canada. Specimens were introduced to Europe in the middle of the 17th century and have feral. By the middle of the 18th century, the neophyte was already widespread across Central Europe. Today the Canadian fleabane has been introduced around the world and is only less common in the tropics, subtropics and the Arctic. After the Second World War , the Canadian fleabane was the second most common rubble plant in bombed-out Stuttgart ; in frequency after the white goosefoot ( Chenopodium album ) and before the coltsfoot ( Tussilago farfara ).

The Canadian fleabane is common in gappy weed corridors , in pavement joints, on rubble sites, paths, dams, in fields and fallow land or in fields or burned areas in the forest. It thrives on moderately nitrogen-rich, preferably sandy soils . The Canadian fleabane is a warmth-loving light plant and is accordingly lacking in areas with a harsh climate. According to Ellenberg , it is an order character type of the Rauken societies or annual ruderal societies ( Sisymbrietalia ). According to Oberdorfer , it is a weak character species of the Conyzo-Lactucetum serriolae from the Sisymbrion association in Central Europe.

ingredients

It contains essential oils with lime and tannins .

edibility

From April to July the leaves can be used in herbal mixtures, herb butter or herb salt. The taste is spicy bitter.

swell

literature

  • John L. Strother: Conyza canadensis. In: Flora of North America Editorial Committee (Ed.): Flora of North America North of Mexico . Volume 20: Magnoliophyta: Asteridae, part 7: Asteraceae, part 2 (Astereae, Senecioneae). Oxford University Press, New York / Oxford a. a. 2006, ISBN 0-19-530564-7 , pp. 350 (English). , online.

Individual evidence

  1. ^ Georg August Pritzel , Carl Jessen : The German folk names of plants. New contribution to the German linguistic treasure. Philipp Cohen, Hannover 1882, page 144. ( online ).
  2. ↑ a b c d Oskar Sebald, Siegmund Seybold, Georg Philippi, Arno Wörz (ed.): The fern and flowering plants of Baden-Württemberg . tape 6 : Special part (Spermatophyta, subclass Asteridae): Valerianaceae to Asteraceae . Eugen Ulmer, Stuttgart (Hohenheim) 1996, ISBN 3-8001-3343-1 , p. 83 .
  3. ↑ a b c Dietmar Aichele, Heinz-Werner Schwegler: The flowering plants of Central Europe . 2nd Edition. tape 4 : Nightshade plants to daisy plants . Franckh-Kosmos, Stuttgart 2000, ISBN 3-440-08048-X , p. 320 .
  4. ↑ a b c Erich Oberdorfer : Plant-sociological excursion flora for Germany and neighboring areas . With the collaboration of Angelika Schwabe and Theo Müller. 8th, heavily revised and expanded edition. Eugen Ulmer, Stuttgart (Hohenheim) 2001, ISBN 3-8001-3131-5 , pp.  915-916 .
  5. ^ Glyphosate Resistant Weeds. SourceWatch, accessed August 30, 2019.
  6. ^ W. Kreh: Amounts of seeds produced on the Stuttgart rubble. In: Yearbooks of the Association of Fatherland Natural History Württemberg, 110th year, pages 212–215, Stuttgart 1955.

Web links

Commons : Canadian Fleabane  - Album of Pictures