Sonchus arvensis, the field milk thistle, field sowthistle, perennial sow-thistle, corn sow thistle, dindle, gutweed, swine thistle, or tree sow thistle, is a species of flowering plant in the daisy family Asteraceae. S. arvensis often occurs in annual crop fields and may cause substantial yield losses.
The plant grows up to 1.5 metres (4 ft 11 in) in height, with leaves 10–35 cm (4–13 3⁄4 in) long and 4–14 cm (1 1⁄2–5 1⁄2 in) wide. It produces conspicuous yellow flowerheads about 3–5 cm (1 1⁄4–2 in) wide, which are visited by various types of insects—especially hoverflies of the genus Eristalis.
Sonchus arvensis is native to Europe, where it is widespread across most of the continent. It has also become naturalized in many other regions, and is considered an invasive noxious weed in some places, such as North America (including Prince Edward Island), Russia, New Zealand, United Kingdom and Australia.
It grows in areas such as pastures, roadsides, bushlands and the shorelines of lakes, rivers and sea coast.
How to get rid of:
Sowthistle spreads vegetativley as well as by seeds and rhizomes so control can be somewhat difficult. To gain control of the area they are growing in now cover the plants with newspaper or cardboard and cover that with a mulch material, or dig them out.