Cotton Thistles

Onopordum, or cottonthistle, is a genus of plants in the tribe Cardueae within the family Asteraceae. They are native to southern Europe, northern Africa, the Canary Islands, the Caucasus, and southwest and central Asia. They are a ruderal species and grow on disturbed land, roadsides, arable land and pastures.

They are biennials (rarely short-lived perennials) with branched, spinose winged stems, growing 0.5–3 m tall. In the first season they form a basal rosette of gray-green felted leaves and rarely a few flower heads. In the second season they grow rapidly to their final height, flowering extensively, and then die off after seed maturation.

The leaves are dentate or shallowly lobed to compound with several pinnatifid or deeply cut leaflets, and strongly spiny. The terminal flower head is typical for thistles, a semi-spherical to ovoid capitulum with purple (seldom white or pink) disc florets. There are no ray florets. The receptacle is glabrous with dentate margins. The tube of the corolla is slender, sac-shaped and symmetrical. The anthers have awl-shaped outgrowths on the top. The capitula have several overlapping rows of leathery basal simple linear-lanceolate spines. These are smooth to slightly pubescent.

These plants propagate only by seed. The seed heads mature in mid-summer, releasing their seeds. The fruit is a glabrous achene, 4–6 mm long and with 4-50 ribs. The pappus consists of many rows of simple, fine to minutely rough hairs, united in a circular base.

Onopordum species are used as food plants by the larvae of some Lepidoptera species including Coleophora onopordiella (feeds exclusively on O. acanthium).

In the Greek island of Crete a native species called agriagginara (αγριαγγινάρα) or koufoti (κουφωτοί) has its heads (flowers) and tender leaves eaten raw by the locals.

Species

Onopordum acanthium L. - Cotton thistle, Scotch thistle, Scotch common-thistle, heraldic thistle, woolly thistle - widespread across Europe and temperate Asia

Onopordum acaulon L. - Stemless thistle, horse thistle - France, Spain, Algeria, Morocco, Tunisia

Onopordum alexandrinum Boiss. - Egypt, Palestine, Lebanon, Syria, Israel, Jordan

Onopordum algeriense (Munby) Pomel - Algeria

Onopordum ambiguum Fresen. - Egypt, Palestine, Lebanon, Syria, Israel, Jordan

Onopordum anatolicum (Boiss.) Eig. - Turkey

Onopordum arenarium M.Hossain & M.A.A.Al-Sarraf - Algeria, Morocco, Tunisia, Libya

Onopordum armenum Grossh. - Caucasus, Iran, Turkey

Onopordum blancheanum (Eig) Danin - Israel, Palestine, Jordan, Syria, Lebanon

Onopordum boissierianum Raab-Straube & Greuter - Turkey

Onopordum bracteatum Boiss. & Heldr. - Greece, Turkey, Cyprus

Onopordum canum Eig - Iran, Jordan, Israel, Turkey

Onopordum carduchorum Bornm. & Beauverd - Lebanon, Syria, Turkey, Iran

Onopordum carduelium Bolle - Canary Islands

Onopordum carduiforme Boiss. - Egypt, Palestine, Lebanon, Syria, Israel, Jordan

Onopordum carmanicum (Bornm.) Bornm. - Iran

Onopordum caulescens d'Urv. - Greece

Onopordum cinereum Grossh. - Caucasus, Turkey, Iran, Turkmenistan, Afghanistan

Onopordum corymbosum Willk. - France, Spain

Onopordum cynarocephalum Boiss. & Blanche - Palestine, Lebanon, Syria, Israel, Jordan

Onopordum cyrenaicum Maire & Weiller - Libya

Onopordum dissectum Murb. - Spain, Morocco

Onopordum dyris Maire - Morocco

Onopordum elongatum Lam.

Onopordum eriocephalum Rouy - France

Onopordum espinae Coss.

Onopordum heteracanthum C.A.Mey. - Caucasus, Lebanon, Turkey, Syria, Palestine, Iran, Afghanistan, Saudi Arabia

Onopordum horridum Viv. - Italy

Onopordum illyricum L. - Illyrian thistle, Illyrian cottonthistle - Mediterranean

Onopordum leptolepis DC. - from Palestine to Altay + Xinjiang

Onopordum macracanthum Schousb. - Spain, Portugal, Italy, Morocco, Algeria

Onopordum macrocanthum d'Urv.

Onopordum macrocephalum Eig - Palestine, Lebanon, Syria, Israel, Jordan

Onopordum mesatlanticum Emb. & Maire - Morocco

Onopordum micropterum Pau - Spain, Canary Islands

Onopordum minor L. - Iran

Onopordum myriacanthum Boiss. - Greece, Turkey, Bulgaria

Onopordum nervosum Boiss. - Moor's cottonthistle - Spain, Portugal

Onopordum parnassicum Boiss. & Heldr. - Greece, Turkey

Onopordum platylepis (Coss. ex Murb.) Murb. - Libya, Tunisia

Onopordum polycephalum Boiss. - Turkey

Onopordum prjachinii Tamamsch. - Uzbekistan, Kyrgyzstan, Tajikistan

Onopordum seravschanicum Tamamsch. - Uzbekistan, Kyrgyzstan, Tajikistan

Onopordum sibthorpianum Boiss. & Heldr. - Greece, Sicily, Malta, Turkey, North Macedonia, Saudi Arabia

Onopordum tauricum Willd. - Turkish thistle, Taurian thistle, Taurus cottonthistle, bull cottonthistle - southern + central Europe, Ukraine, Middle East

Onopordum turcicum Danin - Turkey

Onopordum wallianum Maire - Morocco

Natural hybrids

Onopordum × brevicaule (Onopordum acaulon × Onopordum acanthium )

Onopordum × erectum (Onopordum nervosum ssp. castellanum × Onopordum tauricum ssp. corymbosum )

Onopordum × macronervosum (Onopordum nervosum × Onopordum macrocanthum)

Onopordum × onubense (Onopordum dissectum × Onopordum macrocanthum)

Onopordum × spinosissimum (Onopordum illyricum × Onopordum acanthium)