Gronovius' silk

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Gronovius' silk
Systematics
Asterids
Euasterids I
Order : Nightshade (Solanales)
Family : Bindweed family (Convolvulaceae)
Genre : Silk ( cuscuta )
Type : Gronovius' silk
Scientific name
Cuscuta gronovii
Willd. ex Roem. & Schult.
Stems of Cuscuta gronovii
illustration
Capsule fruits

The willow silk or Gronovius' silk ( Cuscuta gronovii ) is a plant of the genus silk ( Cuscuta ) in the family of wind plants (Convolvulaceae). This parasite is widespread mainly in North America .

description

Vegetative characteristics

Willow silk is an annual herbaceous plant . The yellow to orange stems are medium to fine with a diameter of 0.4 to 0.8 millimeters.

Generative characteristics

The panicle-like inflorescences are loose or dense and contain 7 to 40 almost sessile to stalked flowers . The flower stalks are 1 to 4.5 millimeters long.

The hermaphrodite flowers are usually five-fold, but can rarely be four-fold. The inflorescence is 2 to 4, rarely up to 4.7 millimeters, white and membranous. There may be a few to many translucent, glandular milk tubes in the calyx , in the crown , on the ovary and on the capsule . The calyx is cup-shaped to briefly bell-shaped and usually extends to half of the corolla tube. The sepals are free for about 1/2 to 2/3 of the length. The calyx lobes are ovate to almost round, the tip is rounded, and they overlap at the base. The corolla tube is bell-shaped with a length of usually 1.5 to 2.5 (1 to 3) millimeters. The corolla lobes are protruding, mostly ovoid, rounded blunt and are 1/2 to 1/3 as long as the corolla tube. The stamens are beyond the crown. The anthers are ovate to elongated with a length of 0.3 to 0.6 millimeters. The stamens are 0.4 to 0.7, rarely up to 1 millimeter long. Between the stamens there are elongated scales that are deeply frayed at the tip and reach to the stamens. The two styles are slender and sometimes slightly awl-shaped. With a length of 1.2 to 2.2 millimeters, rarely only 0.6 millimeters, the style is shorter or as long as the ovary. The scars are head-shaped and spherical.

The capsule fruits that do not pop up or pop up irregularly are egg-shaped to spherical-conical or almost inverted-pear-shaped with a length of 2.5 to 4.5, rarely up to 5.2 millimeters and a diameter of 2 to 4, rarely up to 5 millimeters . The durable corolla encloses or sits on the fruit. There are two to four seeds in each fruit .

The number of chromosomes is 2n = 60.

ecology

Cuscuta gronovii is a therophyte . The willow silk is a full parasite (holoparasite). It parasits on Brassica nigra , Urtica or Salix .

Occurrence

Cuscuta gronovii is widespread in North America in from Canada to the USA and occurs on Hispaniola . For example, it is a neophyte in Europe , where it grows along watercourses. It grows on fresh, nutrient-rich alluvial soil. It is a characteristic species of the association Senecion fluviatilis.

Systematics

Cuscuta gronovii was first published in 1820 by Carl Ludwig Willdenow in Johann Jacob Römer and Joseph August Schultes . The specific epithet gronovii honors the Dutch botanist Jan Frederik Gronovius , from whom the probably oldest mention of this species comes.

Of Cuscuta gronovii there are about three varieties:

  • Cuscuta gronovii var. Calyptrata Engelm. : It occurs in the southern, central and eastern United States.
  • Cuscuta gronovii Willd. ex Roem. & Schult. var. gronovii : It occurs from Canada to the USA and on Hispaniola.
  • Cuscuta gronovii var. Latiflora Engelm. : It only occurs in the USA.

swell

  • Mihai Costea, François J. Tardif: The biology of Canadian weeds. 133. Cuscuta campestris Yuncker, C. gronovii Willd. ex Schult., C. umbrosa Beyr. ex Hook., C. epithymum (L.) L. and C. epilinum Weihe. In: Canadian Journal of Plant Science , 2006. Pages 293-316.

Individual evidence

  1. ↑ 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.  774 .
  2. ↑ Cuscuta gronovii Willd. ex Roem. & Schult., Gronovius silk. In: FloraWeb.de.
  3. ↑ a b c d e f Rafaël Govaerts (Ed.): Cuscuta grovovii. In: World Checklist of Selected Plant Families (WCSP) - The Board of Trustees of the Royal Botanic Gardens, Kew . Retrieved February 4, 2016.

Web links

Commons : Willow silk ( Cuscuta gronovii )  - Collection of images, videos and audio files