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Biennials.  Taprooted, usually with a single, tall, stout stem.  Stems tend to be pubescent toward the base, but become glabrous and glaucous upwards.  Sap is milky white.  Typical height is 4 to 8+ feet!

The overall inflorescence is crowded, cylindrical or diamond-shaped in outline, often peaked; usually taller than broad, with many ascending to widely spreading, short branches, and many, rather small flower heads.  Flowering branches tend to be located in the upper third of the plant.

Flower heads are ligulate.  All florets are bisexual and fertile.  Corollas are bluish, varying to white.  Involucres are glabrous, initially cylindrical in shape, becoming swollen at base in age (i.e., vase shaped), 10-14 mm tall (in fruit).

Basal and lowermost stem leaves are usually deciduous by flowering.  Primary stem leaves are broadly lanceolate to oblanceolate in outline, deeply lobed and toothed.  Uppermost leaves are greately reduced in size.

Cypselae are dark brown, flattened, with numerous longitudinal nerves and a very short beakPappus bristles are grayish-white.

Plants of fields, roadsides, thickets, disturbed areas, woodland edges.  Flowers late July through August.  Native.

Similar species:  Lactuca canadensis and Lactuca serriola.

For additional information and comparisons with other species, see my article:  Lactuca Additional Information.

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