Prickly lettuce Lactuca serriola L.
Life cycle: summer or winter annual
Habitat: disturbed habitats
General description: Erect, solitary stem reaching heights of 12 – 40”. Plant initially forms a basal rosette. Young leaves on rosettes are club-shaped with spiny, wavy or lobed margins. Leaves found on elongated stems are variable, with lobes or wavy margins with fine teeth and a conspicuous midvein. Base of blade clasps the stem. The midvein on underside of leaves has stiff bristles. Stems and leaves have milky sap. Individual composite flower heads have numerous yellow, toothed ray flowers approximately 1/3” long. The terminal stem is many-branched with numerous flower heads in a cone-shaped arrangement. Seeds are attached to a ‘fluffy’ pappus for wind dispersal.
Key ID traits: Stiff bristles on underside of midrib, milky sap in leaves and stem, C-shaped sinus between leaf lobes..
Similar species: Prickly lettuce has a similar growth habit and is found in similar habitats to the sowthistles (annual, prickly, perennial) and other wild lettuces (Lactuca spp.). However, the bristles on the underside of the midvein and milky sap simplify distinguishing prickly lettuce from these similar species.