Carduus acanthoides Seeds | Spiny Plumeless Thistle
LATIN NAME: Carduus acanthoides
COMMON NAME: Spiny Plumeless Thistle
Plant Profile
Spiny plumeless thistle is a bristly biennial of the daisy family, native to Europe and western Asia and introduced to North America, southern South America and Australia. It forms a flat rosette of spine-edged leaves in its first year, then a branching, winged stem thirty to a hundred and fifty centimetres tall, armed along its full length with sharp spines.
The flower heads are small, purple-pink and narrow, without the long ray florets of some thistles, and they ripen into heavy seed crops that feed goldfinches. It is a declared noxious weed in several countries, and it spreads rapidly in overgrazed pasture and along roadsides.
Science & Biotechnology
The species is studied mainly as an invasive plant. Research has measured its seed production, which can reach thousands of seeds per plant, and the way the seed bank persists in soil for years. Biological control programmes in North America have tested weevils and flies that feed in the flower heads, following the model used against musk thistle, though results have been mixed.
Work in Europe has looked at the plant’s role in supporting pollinators and seed-eating birds, which complicates its status as a pure weed. Studies of its germination show that seed needs light and a period of cold, which is why it appears in disturbed ground and disappears under a dense sward.
Uses & Benefits
It has no real garden value, and its main practical importance is as a weed of pasture, roadsides and disturbed ground, where the spines deter grazing and the plant spreads quickly in overgrazed paddocks.
The young stems can be peeled and eaten, as with other thistles, and the plant shares the liver-tonic folk reputation of its relatives, though it is far less studied than milk thistle. Its seed is a useful winter food for finches, and the flowers are visited by bees and hoverflies in summer.
Its spines make it easy to identify and unpleasant to handle without gloves.
In Australia it is a weed of lucerne and cereal crops, and it is controlled by grazing and cultivation.
Growing from Seed
Sow in spring or autumn, five millimetres deep, at 15-20C. Germination is fast and the plant grows quickly into a rosette. It needs full sun and open ground, and it will colonise any bare, disturbed soil.
If you grow it for study, cut the flower heads before they set seed, since a single plant can populate a large area. It is not a plant to encourage near pasture or in a garden with children, and gloves are needed when handling the rosette.
The rosette is frost hardy and needs no protection in winter.
Seed should be sown on the surface, since light aids germination.
Cultivation of the rosette before it bolts is the most effective control.
Our Take
Spiny plumeless thistle is a weed to recognise rather than to grow, and its spines make that easy. Its seed feeds finches, but it has no place in a garden.
Related Reading
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