Sow thistle most often refers to yellow flowered, thistle-like plants in the genus Sonchus.
Sow thistle may also refer to: Cicerbita, a genus of plants related to Sonchus, with blue, white, or yellow flowers.
See also Reichardia tingitana, false sow thistle Sonchus asper, the prickly sow-thistle Sonchus oleraceus, common sowthistle