Synonym:   Lactuca scariola  L.

              

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Annuals/Biennials.  Taprooted, often with a single stem, though robust plants may have several stems.  Stems tend to be prickly toward the base, but become glabrous and glaucous upwards.  Sap is milky white.  Typical height is 3 to 5 feet.

The overall inflorescence is usually as broad as tall, flat- or round-topped, or sometimes tall and slender for smaller plants.  Branches are ascending to spreading, with numerous, 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 pale yellow, 5-toothed.  Involucres are glabrous (sometimes minutely papillate), initially cylindrical in shape, becoming swollen at base in age (i.e., vase shaped), 10-15 mm tall (in fruit)

Basal and lowermost stem leaves are typically deciduous by flowering.  Primary stem leaves are oblong/elliptic in outline, lobed or (less frequently) unlobed, with minutely toothed margins.  Upper sides of leaves are glabrous; the lower sides are prickly along the midveins.  Leaf bases are conspicuously auriculate clasping and twisted, such that leaves are spreading outwards, ascending or erect in orientation.

Cypselae are grayish or light brown, flattened, with multiple nerves, and a long, very slender beak.

Plants of fields, roadsides, open disturbed areas.  Flowers late July to September.  Not native..

Similar species:  Lactuca canadensis and Lactuca biennis.

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

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