Illyrian donkey thistle
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Illyrian donkey thistle ( Onopordum illyricum ) |
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The Illyrian donkey thistle ( Onopordum illyricum ) is a species of donkey thistle ( Onopordum ) within the sunflower family (Asteraceae). It grows in the Mediterranean. In Australia, where it was introduced as an ornamental plant, it has evolved into an invasive neophyte that also causes economic damage in pastureland.
description
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Vegetative characteristics
As with all donkey thistles, it is a monocarpic , biennial perennial that forms a leaf rosette with a thick taproot in the first year after germination, from which the flowering stem grows in the second year . This reaches heights of 30 to 130 (up to 250) centimeters. Stems and leaves are mostly hairy, woolly-tomentose and therefore more or less whitish to yellow-gray in color. The stem is covered with deciduous leaf wings, which are densely thorny and not nervous about the network .
The sessile (sessile), elongated-lanceolate leaves reach 55 centimeters in length and 15 centimeters in width, they are one to two pinnate to pinnate with eight to ten spaced sections, these are triangular-wedge-shaped, they too end in long thorns. The leaf veins on the underside of the leaves are indistinct.
Generative characteristics
The cup-shaped inflorescences usually sit individually at the end of the branches of the stem, which is generally not very branched. The flower heads are spherical to ovoid with a height of 3 to 5 centimeters and a diameter of 4 to 6 centimeters. They are hairy like a cobweb on the underside. The involucre consists of roof-tile-like overlapping bracts , which are more or less adjacent or the middle and outer ones are curved back in the upper half and thus protrude. The green, occasionally red bracts are 5 to 7 millimeters wide and each has a thorn at its tip. The corolla of the tubular flowers is purple in color and 25 to 35 millimeters long.
The ( achenes ) are 4 to 5 millimeters long. Your feathered pappus is 10 to 12 millimeters long.
Both subspecies of the Illyrian donkey thistle are diploid with a chromosome number of 2n = 34. The flowering period on Crete extends from May to August.
Systematics
The scientific name Onopordum illyricum was first published in 1753 by Carl von Linné in Species Plantarum .
A distinction is made between two subspecies, including the nominate form :
- Onopordum illyricum subsp. illyricum : Stems and leaves are white or gray tomentose, the leaf wings on the stem are up to 10 millimeters wide with thorns up to 5 millimeters long. The corolla is 25 to 30 millimeters long. The bracts have a thorn up to 3 millimeters long; the outer ones are close-fitting to curved back. This subspecies is more widespread in western Mediterranean, from Albania and Croatia to the west. It was once collected as an adventitious plant in Romania.
- Onopordum illyricum subsp. cardunculus ( Boiss. ) Franco : it differs from the subsp. illyricum by 30 to 35 millimeters long corollas and by upright bracts that are only slightly curved back on the outer bracts and end in a thorn up to 2 millimeters long. This subspecies is more widespread in the Eastern Mediterranean and occurs in Sicily, the Balkan Peninsula, Crete and the Middle East.
Onopordum horridum Viv. (Syn .: Onopordum illyricum subsp. Horridum ( Viv. ) Franco ) counts Euro + Med PlantBase as a separate species.
Occurrence
The Illyrian donkey thistle occurs in southern Europe and the Middle East , from Portugal in the west to Syria in the east, including the Balearic Islands , Sicily and Crete , but is absent in Cyprus. The deposits on the Balkan Peninsula reach southern Bulgaria. It grows on wasteland, ruderal sites and near stables. In Crete it inhabits altitudes from 0 to 1200 meters.
The Illyrian donkey thistle as a neophyte
Similar to the common donkey thistle ( Onopordum acanthium ), the Illyrian donkey thistle was imported to Australia as an ornamental plant in the 19th century and has grown wild there in the southeast of the continent. Hybrids between them are even more common there than the pure species , which are far more common here than in the area of origin (where they also occur very rarely). The nitrogen-loving species mainly spreads in fertilized pastureland, where it is far more common than in natural plant formations. In parts of southeast Australia, it is considered the most important pasture weed. The infected stocks are estimated at around one million hectares.
In the 1980s, CSIRO initiated extensive research into the biological control of Illyrian donkey thistle . As a result, some biological antagonists were imported and released. These are the weevils Larinus latus , Lixus cardui and Trichosirocalus briesei and the owl butterfly Eublemma amoena , a whole arsenal of herbivores, some of which attack the flower heads and others the leaves and stems. The drill fly Tephritis postica , the flower fly Botanophila spinosa and the cicada Tettigometra sulphurea were also released, but did not establish themselves. The control is rated as successful, with the beetles Larinus latus and Lixus cardui , which both attack the flower heads , having the greatest effect. Larinus latus also attacks the flower baskets in the natural area (Greece), in which the female lays eggs, whereupon the larvae eat the ovules. Here, 80 to 100 percent of the flower heads are affected regionally.
The Illyrian donkey thistle later appeared feral in the Bay of San Francisco , California, North America, where control measures were immediately initiated. The aim is, according to the Australian experience, to prevent the establishment of the Illyrian donkey thistle by exterminating all wildlife.
Individual evidence
- ↑ a b David J. Keil: Onopordum. In: Flora of North America Editorial Committee (Ed.): Flora of North America North of Mexico . Volume 19: Magnoliophyta: Asteridae, part 6: Asteraceae, part 1 (Mutisieae – Anthemideae). Oxford University Press, New York / Oxford a. a. 2006, ISBN 0-19-530563-9 , pp. 87 (English, same text online as the printed work ). .
- ↑ a b c d J. do Amaral Franco: 125. Genus Onopordum. In: TG Tutin, VH Heywood, NA Burges, DM Moore, DH Valentine, SM Walters, DA Webb (eds.): Flora Europaea . Volume 4: Plantaginaceae to Compositae (and Rubiaceae) . Cambridge University Press, Cambridge 1976, ISBN 0-521-08717-1 , pp. 247 (English, limited preview in Google Book search).
- ↑ CCDB Chromosome Counts Database. Onopordum illyricum .
- ↑ a b c d Ralf Jahn, Peter Schönfelder: Excursion flora for Crete . With contributions by Alfred Mayer and Martin Scheuerer. Eugen Ulmer, Stuttgart (Hohenheim) 1995, ISBN 3-8001-3478-0 , p. 324-325 .
- ↑ Carl von Linné: Species Plantarum. Volume 2, Lars Salvius, Stockholm 1753, p. 827 ( digitized version ).
- ↑ a b c d e Werner Greuter: Compositae (pro parte majore). Onopordum illyricum. In: Werner Greuter, Eckhard von Raab-Straube (ed.): Compositae. Euro + Med Plantbase - the information resource for Euro-Mediterranean plant diversity. Berlin from 2006.
- ↑ Peter Hein: Onopordum illyricum subsp. illyricum. In: Werner Greuter, Eckhard von Raab-Straube (ed.): Euro + Med Notulae, 1 (= Notulae ad floram euro-mediterraneam pertinentes No. 16). In: Willdenowia. Volume 35, No. 2, 2005, pp. 223-239 (here: p. 236), DOI: 10.3372 / wi.35.35201 .
- ↑ David Briese: Onopordum acanthium L. - Scotch thistle Onopordum illyricum L. - Illyrian thistle hybrids. In Mic Julien, Rachel McFadyen, Jim Cullen (Eds.): Biological Control of Weeds in Australia. CSIRO Publishing, 2012, ISBN 978-0-643-09993-7 , pp. 416–424, limited preview in Google Book Search.
- ↑ Polly Lehtonen: Weed Risk Assessment for Onopordum illyricum L. - Illyrian thistle. In: Sarah Reichard, Lizbeth Seebacher: Analysis and Assessment of the Invasive risk of Onopordum illyricum. Report, University of Washington, College of Forest Resources, Center for Urban Horticulture 2002, Addendum ( PDF file ).
Web links
- Factsheet Onopordum illyricum. In: Weeds of Australia, Biosecurity Queensland Edition , accessed February 17, 2016
- Onopordum illyricum from Flora Italiana , accessed February 17, 2016