Cotton thistle

What does Cotton thistle look like?

Cotton thistle is a striking plant that can reach up to 3 meters in height and spread nearly 1.5 meters wide. Its leaves are deeply lobed, covered in white, cotton-like hairs, and edged with sharp, stiff spines. The stems are thick and winged with spiny extensions. In summer, it produces globe-shaped flower heads, 2 to 6 centimeters across, in shades from dark pink to lavender. Each flower sits above a ring of long, outward-pointing bracts tipped with spines.

Where does Cotton thistle come from?

This thistle is native to a broad area stretching from southwestern Europe across to Kazakhstan and up into central Scandinavia. It prefers regions with dry summers and fertile soils, such as pastures, fields, and disturbed ground. The plant has been introduced to many other parts of the world, including North America and Australia, where it has spread rapidly and is now considered a weed in some places. Its name comes from the cottony hairs on its leaves, and the genus name has roots in ancient Greek words for 'donkey', 'to fart', and 'thorn'.

When and how Cotton thistle blooms

Cotton thistle grows as a rosette of leaves in its first year, storing energy in a thick taproot. In its second year, it sends up tall, branched stems topped with flowers. Seeds are produced in large numbers after flowering and are mainly spread by wind, animals, and water. The plant thrives in sunny, open areas with well-drained, nutrient-rich soils and can germinate at various times depending on moisture and temperature.

How Cotton thistle is used

People have grown cotton thistle for its dramatic look in gardens, though its spines make it difficult to handle. In the past, the flower base was eaten like artichoke, and the soft hairs from the stem were sometimes used to stuff pillows. Oil from its seeds has served for burning and cooking. The plant also provides nectar for pollinators and seeds for birds.

Kinds of Cotton thistle

There are three accepted subspecies: the widespread Onopordum acanthium subsp. acanthium, subsp. gautieri found in France and Spain, and subsp. parnassicum in Greece. Cotton thistle can hybridize with related thistles, especially in Australia.

What Cotton thistle means

Cotton thistle is sometimes called Scottish thistle, but the national flower of Scotland is a different species. Its bold form and spiny leaves have made it a symbol in heraldry. In many countries, it is considered an invasive weed, forming dense stands that can block access for livestock and people.

Questions people ask about Cotton thistle

Good reading and sources

• USDA Plants DatabaseUS Department of Agriculture, Article
• Onopordum acanthiumRoyal Horticultural Society, Article
• Plants of the World OnlineRoyal Botanic Gardens, Kew, Plant database
• Where it has been recordedGBIF, Plant database
• Sightings and photos by naturalistsiNaturalist, Plant database

• Onopordum acanthium on WikipediaEncyclopedia
• More photos on Wikimedia CommonsPhotos
• Wikidata recordOpen data