Lactuca serriola is an annual or biennial that can reach heights of 6 ft. (1.8 m).
Foliage
Cauline leaves (on the stem) are alternate, 2-14 in. (5-36 cm) long and become smaller up the stem. Leaves have a conspicuous, white midvein with the underside of the vein covered with many prickles.
Flowers
In the mid-to-late summer, 0.5 in. (1.3 cm) wide, yellow flowers develop in a branched inflorescence at the apex of the stem.
Fruit
Flowers produce dandelion-like seeds.
Ecological Threat
Lactuca serriola is native to the Mediterranean region and occurs along roadsides, in abandoned fields, and other disturbed areas. It was accidentally introduced into North America in the late 1890s, possibly as a contaminant in seed.