Lactuca saligna L.

Willow-Leaved Lettuce

© SRTurner

Family - Asteraceae/Cichorieae

Habit - Annual or biennial forb with milky sap.

Stem - Erect, to 1 m or more, glabrous, sometimes glaucous, light tan; latex white.

	Stem and leaves.
© SRTurner

Leaves - Well developed along stem, to 15 cm long, narrow, linear and unlobed or narrowly elliptic-lanceolate in outline, sessile and clasping, auriculate, glabrous or occasionally with short hairs along abaxial midvein.

	Stem and leaves.
© SRTurner

	Stem and leaves.
© SRTurner

Inflorescences - Narrow, spikelike panicles with 30-100 or more heads.

	Inflorescence.
© SRTurner

Heads - Involucres cylindrical, 7-9 mm long, with about 17 involucral bracts. Receptacle naked.

	Involucre.
© SRTurner

Flowers - Ligulate florets 11-14, pale yellow, sometimes with a bluish- or purplish-tinged undersurface. Pappus of 4-6 mm bristles.

	Flowering head.
© SRTurner

Fruits - Achenes with the body 3.0-3.5 mm long, about 1.0-1.5 mm wide, greenish brown to dark gray, flattened, with 5-7 conspicuous nerves or ridges on each face, tapered abruptly to a slender beak 1.5-2.0 times as long as the body.

	Fruits.
© SRTurner

Flowering - July - October.

Habitat - Streambanks, bottomland forest openings, margins of glades, disturbed portions of bottomland prairies, ditches, levees, fields, gardens, pastures, railroads, roadsides, open, disturbed areas.

Origin - Native to Eurasia

Lookalikes - Broadly, L. serriola, L. canadensis.

Other info. - This distinctive introduced lettuce occurs across Missouri, though it is scattered and somewhat uncommon. There are two main ranges in the continental U.S., one in a band extending from eastern Kansas eastward through Pennsylvania, the other in areas approaching the west coast. The plant is recognized by its very narrow leaves, which exude milky white sap if broken, and yellow ligulate flower heads.

The epithet saligna means "willow-like," referring to the narrow leaves. This species is less commonly encountered than the other small-flowered, yellow species of Lactuca (L. serriola and L. canadensis). Some authors have divided this species into multiple infraspecific types based upon leaf shape, but since these forms tend to occur within the same population, the division is questionable.

Photographs taken in Labadie, Franklin County, MO, 8-1-2012 (SRTurner).