Sow thistle’s origins lie in Western Asia and Europe. From its home continents, it would eventually make its way all over the world. The common name comes from the fact that pigs are attracted to it. Nicknames for it include hare thistle and hare lettuce because one popular way to use it is as rabbit food.
There are several closely related sow thistles with the most common being Sonchus oleraceus. Sonchus arvensis and Sonchus asper look similar to Sonchus oleraceus and are often confused with it. The name Sonchus comes from Ancient Greek meaning hollow and refers to the sow thistle’s hollow stem.
Sow thistle was consumed as a salad green in Ancient Greece. The Ancient Greeks believed it to be a particularly nutritious green. According to Pliny, Theseus ate a bowl of sow thistles before his encounter with the bull of Marathon.
It most likely made its way to the United States via contaminated seed and was first noticed in Pennsylvania in 1814. At this point in history, new plants were being introduced to the continent and spread via the railroads as well as by contaminated hay and even packing materials. These days, you can find sow thistle all over the North American continent and it is considered an invasive species; however, it is not as common in Southern and Central states.