Creeping thistle is one of many different types of thistles, which is characterised by its creeping lateral roots that grow horizontally. It is a perennial weed that can spread over verge large areas, making it very difficult to control and eradicate, especially if allowed to become established.
These lateral roots are very brittle and readily snap or break off when cultivating the soil or trying to dig up the plants. Even small pieces of these roots will reshoot to produce a new plant.
As the roots spread for some distance, creeping thistle quickly produces large clumps. And, as the leaves are very spiny, these become a real nuisance.
The flowers also produce huge numbers of seeds, which are carried long distances by wind, spreading this weed even further.