Spear (or Black) Thistle Cirsium vulgare
NB These thistles are often mis-called Scotch thistles.
Origin. Eurasia and North Africa.
Distribution in Canberra Region. Widely distributed in woodland and grassland throughout the region but seldom as a dominant species; more scattered than in clumps.
CNP: a persistent invader is almost all parts. CUPP: less.
Farmlands: often some infestation.
Dispersal. Mostly by falling seed; often carried by livestock/kangaroos.
General description and biology
This thistle is often biennial. The rosette remains partially grown for over one year.
An erect herb up to 2 m high. The furrowed hairy stem often branches high up or low down.
Leaves moderately dark green above, covered with prickles and hairs; underneath, pale, downy.
Flower-heads are single or in groups of 2-3, on ends of main stem or on short lateral branches.
Flowering is usually in late summer or autumn. Flowers are light purple.
This thistle is often incorrectly called Scotch thistle.
Control methods
a. Manual methods
Can be cut with loppers/giant secateurs, but better dug out with mattock; small ones hand-pulled.
If cut at ground level (below the first leaves) they don�t usually grow again.
The stems of all but small ones are too tough for brushcutters with nylon blades.
If flowers or seedheads already formed, these should be cut off, bagged and composted/destroyed.
The rosettes can be quite easily cut off just below ground level with a mattock or mini-pick; less easily, with loppers. Getting them at the rosette stage is really the best strategy.
Because biennial, roots may grow deeper, so deeper chipping with mattock is desirable.
b. Chemical methods
As for Variegated thistle; but the time for spraying is later (summer rather than spring).