Donaldson, S. and Hanson Mazet, W. 2010, A Northern Nevada Homeowner's Guide to Identifying and Managing Prickly Lettuce, Extension, University of Nevada, Reno, FS-10-28

Other common names: China lettuce, wild lettuce, compassplant

Scientific name: Lactuca serriola
Family: Asteraceae

Description:
A bushy, much‐branched drought‐tolerant plantthat grows to 5+ feet tall. A common weed of mid‐summer in disturbed areas, prickly lettuce forms a rosette (ground‐hugging form) in winter or early spring and grows flowering stems in summer. All plant parts ooze a milky, sticky sap when broken.

Leaves: Larger below and smaller above; twist at the stem to point upright. They have sharp spines on the underside of the midrib and on the edges, and clasp the stem. Some plants have lobed leaves, and other do not.

Stems: Prickly stems grow from the base of the plant and branch above.

Flowers: Small and yellow with toothed tips on the petals. Blooms from summer to fall.

Seeds: Produces a puffball of wind‐dispersed seeds.

Roots: Grows a deep taproot.

Native to: Europe; naturalized throughout the United States

Where it grows: Gardens, yards, vacant lots, roadsides, urbanareas and other disturbed or unmanaged sites

Life cycle: Winter annual (sprouts in fall or early winter) orsometimes biennial (flowers and dies in the second year)

Reproduction: Reproduces by seed

Control methods:
Preventing seed production is key to controlling this weed. Each prickly lettuce plant can make as many as 2,300 seeds. A single plant can result in a large infestation the following year. The seeds are ready to sprout soon after they disperse. Plants are most easily removed when they are small rosettes.

Mechanical:
Dig, hoe or pull young plants. Use mechanical control methods prior to formation of flowers and seeds. Mowing is not effective, as plants will regrow and flower.

Cultural:
Plant desirable vegetation to compete with prickly lettuce; minimize soil disturbance.

Biological:
Sheep and goats will graze plants.

Chemical:
Apply broadleaf‐selective herbicides or glyphosate on young plants. Glyphosate is nonselective and will damage desirable plants. Herbicides are not very effective once flowering stems have appeared. Herbicide resistance has been reported.

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