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A biennial or winter annual
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Introduced from Europe
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Grows up to 2.5 metres
Nodding Thistle
(Cenchrus longispinus)
Quick Identification
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Flowers (3-5 cm across) are bright purple with spiky bracts that are purple towards the petals fading to green
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Flowers 'nod' to the side on a stem bare of leaves for a length before the flower head
- Leaves are deeply divided and spiny giving a 'sharper' than other thistle species
Impact
Nodding thistle degrades pastures, meadows and native grasslands. Grazing animals avoid the thistle while giving it an advantage over more palatable species.
Management
Stopping seed production is the most effective method. Bagging flowers or seed heads and digging the root will prevent reproduction and regrowth. Biocontrol has been released in the Boundary. Effective herbicides are available.
Flower
Plant flowers from June to October. Each plant has several bright purple flowers on individual stalks each 3 to 5 cm across.
Leaves & Stems
In the first year, the thistle forms a dense, spiny rosette. In the second year, plants grow 2.5 m tall and can have several branching stems. Leaves are deeply divided and spiny, giving a particularly sharp appearance to the plant. The stems have spiny wing until nearing the flower head where the stem becomes smooth.
Roots
A thick taproot becomes hallow at the top.
Reproduction & Dispersal
Plants can regrow from its root if severed, but reproduced via seeds. The seeds are topped by a papery pappus (the tuft of hairy that forms an umbrella at the top of the seed). Seeds can be carried by the wind, machinery, birds and other animals to new sites.
Seeds
Seeds are light brown and 4 mm long. They can remain viable for 10 years.
Preferred Habitat
Nodding thistle prefers open pastures and road sides. They primarily invade disturbed environments but can take root in undisturbed habitats too.
Interesting Facts
The down from the thistle can be used to make paper.
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