prickly lettuce
(Lactuca serriola L.)

Overview

Appearance

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.

Selected Images

Maps

Invasive Listing Sources

• Jil M. Swearingen, Survey of invasive plants occurring on National Park Service lands, 2000-2007
• John Randall, The Nature Conservancy, Survey of TNC Preserves, 1995.
• National Park Service, Mid-Atlantic Exotic Plant Management Team Invasive Plant List
• Nonnative Invasive Species in Southern Forest and Grassland Ecosystems
• WeedUS - Database of Plants Invading Natural Areas in the United States

References