Onopordum illyricum
Encyclopedia
Onopordum illyricum is a species of thistle
known by the common name Illyrian thistle, or Illyrian cottonthistle. It is native to southestern Europe
, but has been introduced into Australia
and California
, where it has become a noxious weed.
The plant is a biennial herb producing an erect, branching, winged, spiny stem known to exceed two meters in maximum height. The spiny leaves may be up to 50 centimeters long and are divided into deep toothed lobes. The inflorescence
bears several large flower heads
each up to 7 centimeters wide. They are lined with spiny, woolly to cobwebby phyllaries
and bear many narrow glandular purple flowers each about 3 centimeters long. The fruit is a cylindrical achene
4 or 5 millimeters long topped with a white pappus
a centimeter in length.
Thistle
Thistle is the common name of a group of flowering plants characterised by leaves with sharp prickles on the margins, mostly in the family Asteraceae. Prickles often occur all over the plant – on surfaces such as those of the stem and flat parts of leaves. These are an adaptation that protects the...
known by the common name Illyrian thistle, or Illyrian cottonthistle. It is native to southestern Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, but has been introduced into Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
and California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, where it has become a noxious weed.
The plant is a biennial herb producing an erect, branching, winged, spiny stem known to exceed two meters in maximum height. The spiny leaves may be up to 50 centimeters long and are divided into deep toothed lobes. The inflorescence
Inflorescence
An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...
bears several large flower heads
Head (botany)
The capitulum is considered the most derived form of inflorescence. Flower heads found outside Asteraceae show lesser degrees of specialization....
each up to 7 centimeters wide. They are lined with spiny, woolly to cobwebby phyllaries
Bract
In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis, or cone scale. Bracts are often different from foliage leaves. They may be smaller, larger, or of a different color, shape, or texture...
and bear many narrow glandular purple flowers each about 3 centimeters long. The fruit is a cylindrical achene
Achene
An achene is a type of simple dry fruit produced by many species of flowering plants. Achenes are monocarpellate and indehiscent...
4 or 5 millimeters long topped with a white pappus
Pappus (flower structure)
The pappus is the modified calyx, the part of an individual disk, ray or ligule floret surrounding the base of the corolla, in flower heads of the plant family Asteraceae. The pappus may be composed of bristles , awns, scales, or may be absent. In some species, the pappus is too small to see...
a centimeter in length.