Botanical description: Sow-thistle, Sonchus olearaceus, is not a thistle at all, although its deeply lobed and serrated leaves suggest an affiliation. The genus is closely related to the wild lettuce, a relationship seen in the same milky sap, mutable leaf shape and yellow dandelion-like flowers. There are no sharp or stiff prickles on the plant and new foliage and stems are covered with a waxy, bluish coating. Leaves often bear a magenta midrib, both early and late in the season. The sow-thistle's yellow flowers are nearly an inch across, blooming from June until October in terminal clusters at the end of stalks. Seeds have a feathery tuft that aids their dispersal, but they do not resemble dandelions in this regard. The plant can grow to four feet in optimal soil, but is more likely to be between one and four feet in tough, urban conditions. A hard frost can reduce the species to mush, but the plant will return in subsequent years as it is a robust perennial. In warmer climates, Sonchus oleraceus remains evergreen throughout the winter.