Common Sow or Milk Thistle

(Sonchus oleraceus) A common annual weed that, if left to grow unhindered, may exceed a height of two metres. Occurring naturally across Europe, Asia and northern Africa, it is now widespread on most continents. Its leaves and stems are mid-green, often with a dark reddish tinge. The stems exude a milky sap when broken, hence one of its two common name. Its flowers, usually produced in terminal clusters, are pale to mid yellow and daisy-like. They are followed by dense heads of seeds, each quite hairy to aid wind and water dispersal. Milk Thistle is a major host plant for aphids – eradication of this weed will reduce aphid populations.