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Red Star Thistle

Centaurea calcitrapa

Please keep in mind that it is illegal to uproot a plant without the landowner's consent and care should be taken at all times not to damage wild plants. Wild plants should never be picked for pleasure and some plants are protected by law.
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Plant Profile

Flowering Months:
Asteraceae (Daisy)
Also in this family:
Alpine Blue Sow-thistle, Alpine Cotula, Alpine Fleabane, Alpine Saw-wort, Annual Ragweed, Annual Sunflower, Argentine Fleabane, Autumn Hawkbit, Autumn Oxeye, Beaked Hawksbeard, Beggarticks, Bilbao Fleabane, Black Knapweed, Black-eyed Susan, Blanketflower, Blue Fleabane, Blue Globe-thistle, Bristly Oxtongue, Broad-leaved Cudweed, Broad-leaved Ragwort, Brown Knapweed, Butterbur, Buttonweed, Cabbage Thistle, Canadian Fleabane, Canadian Goldenrod, Carline Thistle, Chalk Knapweed, Chamois Ragwort, Changing Michaelmas Daisy, Chicory, Chinese Mugwort, Chinese Ragwort, Coltsfoot, Common Blue Sow-thistle, Common Cat's-ear, Common Cudweed, Common Daisy, Common Dandelion, Common Fleabane, Common Goldenrod, Common Groundsel, Common Michaelmas Daisy, Common Mugwort, Common Ragwort, Common Wormwood, Coneflower, Confused Michaelmas Daisy, Corn Chamomile, Corn Marigold, Cornflower, Cotton Thistle, Cottonweed, Creeping Thistle, Daisy Bush, Dwarf Cudweed, Dwarf Thistle, Early Goldenrod, Eastern Groundsel, Eastern Leopardsbane, Elecampane, English Hawkweed, Fen Ragwort, Feverfew, Field Fleawort, Field Wormwood, Fox and Cubs, French Tarragon, Gallant Soldier, Garden Lettuce, Giant Butterbur, Glabrous-headed Hawkweed, Glandular Globe-thistle, Glaucous Michaelmas Daisy, Globe Artichoke, Globe-thistle, Goat's Beard, Golden Ragwort, Golden Samphire, Goldilocks Aster, Grass-leaved Goldenrod, Great Lettuce, Greater Burdock, Greater Knapweed, Grey-headed Hawkweed, Guernsey Fleabane, Hairless Blue Sow-thistle, Hairless Leptinella, Hairy Michaelmas Daisy, Harpur Crewe's Leopardsbane, Hawkweed Oxtongue, Heath Cudweed, Heath Groundsel, Hemp Agrimony, Highland Cudweed, Hoary Mugwort, Hoary Ragwort, Hybrid Knapweed, Intermediate Burdock, Irish Fleabane, Jersey Cudweed, Jerusalem Artichoke, Lance-leaved Hawkweed, Lavender-cotton, Leafless Hawksbeard, Least Lettuce, Leopardplant, Leopardsbane, Leptinella, Lesser Burdock, Lesser Hawkbit, Lesser Sunflower, London Bur-marigold, Magellan Ragwort, Marsh Cudweed, Marsh Hawksbeard, Marsh Ragwort, Marsh Sow-thistle, Marsh Thistle, Meadow Thistle, Melancholy Thistle, Mexican Fleabane, Milk Thistle, Mountain Everlasting, Mouse-ear Hawkweed, Musk Thistle, Narrow-leaved Cudweed, Narrow-leaved Hawkweed, Narrow-leaved Michaelmas Daisy, Narrow-leaved Ragwort, New England Hawkweed, New Zealand Holly, Nipplewort, Nodding Bur-marigold, Northern Hawksbeard, Norwegian Mugwort, Oxeye Daisy, Oxford Ragwort, Pearly Everlasting, Perennial Cornflower, Perennial Ragweed, Perennial Sow-thistle, Perennial Sunflower, Pineapple Mayweed, Plantain-leaved Leopardsbane, Ploughman's Spikenard, Plymouth Thistle, Pontic Blue Sow-thistle, Pot Marigold, Prickly Lettuce, Prickly Sow-thistle, Purple Coltsfoot, Rayed Tansy, Red-seeded Dandelion, Red-tipped Cudweed, Robin's Plantain, Roman Chamomile, Rough Cocklebur, Rough Hawkbit, Rough Hawksbeard, Russian Lettuce, Safflower, Salsify, Saw-wort, Scented Mayweed, Scentless Mayweed, Sea Aster, Sea Mayweed, Sea Wormwood, Seaside Daisy, Shaggy Mouse-ear Hawkweed, Shaggy Soldier, Shasta Daisy, Shetland Mouse-ear Hawkweed, Shrub Ragwort, Sicilian Chamomile, Silver Ragwort, Slender Mugwort, Slender Thistle, Small Cudweed, Small Fleabane, Smooth Cat's-ear, Smooth Hawksbeard, Smooth Sow-thistle, Sneezeweed, Sneezewort, Spear Thistle, Spotted Cat's-ear, Spotted Hawkweed, Sticky Groundsel, Stinking Chamomile, Stinking Hawksbeard, Tall Fleabane, Tall Mouse-ear Hawkweed, Tansy, Thin-leaved Sunflower, Trifid Bur-marigold, Tuberous Thistle, Tyneside Leopardplant, Viper's Grass, Wall Lettuce, Welsh Groundsel, Welted Thistle, White Butterbur, White Buttons, Willdenow's Leopardsbane, Winter Heliotrope, Wood Burdock, Wood Ragwort, Woody Fleabane, Woolly Thistle, Yarrow, Yellow Chamomile, Yellow Fox and Cubs, Yellow Oxeye, Yellow Star Thistle, Yellow Thistle, York Groundsel
Life Cycle:
Maximum Size:
60 centimetres tall
Grassland, meadows, roadsides, wasteland.

Purple, many petals
The inflorescence consists of just a few oval flowerheads. Each flower is up to 1cm long. The flowers have stout, sharp and spiny, yellow bracts. Pollinated by bees, flies, butterflies and moths.
The fruit is an achene without a pappus. The seeds ripen between August and October.
A biennial with many branches. The leaves are pinnately lobed, greyish-green and tipped by a spine.
Other Names:
Caltrap, Caltrop Knapweed, Caltrops, Common Star Thistle, Lovely Thistle, Maize Thorn, Mouse Thorn, Purple Star-thistle, Star Thistle, Starthistle, Thistle Root.
Frequency (UK):
Rarely seen  

Other Information


Centaurea calcitrapa, also known as starthistle or caltrop knapweed, is a perennial herb that is native to Europe and Asia. It has purple, thistle-like flowers that bloom in the summer and is known for its spiky leaves and stems. The plant is often found in meadows, grasslands, and along roadsides, and is considered an invasive species in some states. It is known to displace native plants, and can be difficult to control once established. It is not commonly used for medicinal purposes.


Red Star Thistle, also known as Centaurea calcitrapa, is a beautiful and distinctive plant species that is native to the Mediterranean region. This plant is known for its vibrant and eye-catching blooms, which come in shades of deep red and purple, and can grow up to 2 inches in diameter.

One of the most notable features of Red Star Thistle is its unique and spiky appearance, which can add a touch of texture and interest to any garden or landscape. The plant's bright and bold blooms are often surrounded by deeply-lobed and prickly leaves, which can make it an excellent choice for use as a natural barrier or hedge.

Aside from its visually-appealing qualities, Red Star Thistle is also a popular choice among gardeners and horticulturists because of its hardiness and adaptability. This plant is able to grow in a variety of soil types and conditions, and is highly resistant to disease and pests. This makes it an easy-to-grow and low-maintenance addition to any garden.

Despite its popularity, Red Star Thistle is considered an invasive species in many parts of the world, including the United States and Australia. This is because of its ability to spread quickly and dominate local ecosystems, which can have a negative impact on native plant species. As a result, it is important for gardeners and horticulturists to be mindful of where and how they plant Red Star Thistle in order to minimize its spread and impact on local ecosystems.

Red Star Thistle is a beautiful and unique plant species that can add a touch of color and texture to any garden or landscape. However, it is important to be mindful of its invasiveness and to plant it in a responsible manner in order to minimize its impact on local ecosystems. Whether you are a seasoned gardener or just starting out, Red Star Thistle is a plant that is definitely worth considering for your next landscaping project.

In addition to its ornamental value, Red Star Thistle is also used in traditional medicine for its various health benefits. It has been used for centuries to treat a range of conditions, including respiratory problems, skin ailments, and digestive issues. The plant contains compounds that are believed to have anti-inflammatory, antibacterial, and antifungal properties, making it a popular ingredient in many natural remedies.

Another interesting aspect of Red Star Thistle is its cultural significance. In many cultures, the plant is believed to bring good luck and prosperity, and is often used in traditional celebrations and ceremonies. For example, in Greek folklore, the plant is believed to have been created by the centaur Chiron, who used it to heal wounds.

When it comes to growing Red Star Thistle, it is important to provide the plant with plenty of sunlight and well-drained soil. It is also important to water the plant regularly, but to avoid overwatering, as this can lead to root rot. The plant will typically flower from mid-summer to early fall, and can reach a height of up to 4 feet, depending on growing conditions.

Red Star Thistle is also a popular choice for cut flower arrangements, as its vibrant blooms and interesting texture make it an excellent filler for bouquets and floral arrangements. Whether you are growing it for its ornamental value, medicinal benefits, or cultural significance, Red Star Thistle is a plant that is sure to add a touch of beauty and interest to any garden or landscape.

Red Star Thistle is a versatile and multi-faceted plant species that offers a range of benefits to gardeners and horticulturists. Whether you are growing it for its ornamental value, health benefits, or cultural significance, it is a plant that is definitely worth considering for your next gardening project.

In terms of design and planting, Red Star Thistle can be used in a variety of different ways in the garden. It is a great choice for borders, rock gardens, and naturalized areas, where its bright blooms and spiky texture can be used to create eye-catching and unique displays. The plant also pairs well with other perennials and annuals, and can be used to add interest to mixed borders or flower beds.

Another great way to use Red Star Thistle in the garden is to plant it in mass. When planted in groups, the plant creates a stunning visual impact, as its bright blooms create a sea of vibrant color. This can be particularly effective in large landscapes or public spaces, where the plant can be used to create an eye-catching focal point.

When designing a garden with Red Star Thistle, it is also important to consider its spiky texture and prickly leaves. This can be used to create natural barriers or dividers in the garden, as the plant's spiky appearance can make it an effective deterrent for animals or people. Alternatively, the plant can be used to create a wild and naturalistic feel in the garden, as its spiky texture and bright blooms add interest and texture to any landscape.

In conclusion, Red Star Thistle is a versatile and multi-functional plant that offers a range of benefits to gardeners and horticulturists. Whether you are using it to create a stunning display of color, to create natural barriers or dividers in the garden, or to add interest and texture to your landscape, Red Star Thistle is a plant that is sure to make a big impact in any garden.

Distribution Map

Reproduced by kind permission of the BSBI.

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