Thistles

= = © Copyright CSIRO Australia, (2005) Scotch thistles were probably introduced into Australia by the Europeans in the early 1800s. It wasn't long before they became a pest. There are different types of pests, like the blue thistle, cotton thistle, heraldic thistle and woolly thistle. They might have been introduced because people wanted to have plants that reminded them of their home land, but they probably didn't think of the consequences.