Lactuca serriola is an annual or biennial plant that is commonly considered a weed.
It is the closest wild relative of cultivated lettuce (Lactuca sativa L.), it grows throughout the temperate regions of all major continents including the USA. It was introduced and naturalized in most of the United States from Europe and is common in the Pacific Nortwest. The milky sap it produces is very sticky and bitter. If any part of the plant is torn or broken the sap will cover the area.
The leaves grow along a spiny stem and get progressively smaller as they reach its top. Many flowers are produced and usually appear in the upper part of the plant The plant can be eaten as a salad, although it has something of a bitter taste.