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Prickly Lettuce

Lactuca serriola

Prickly Lettuce, Lactuca serriola, photo © by Michael Plagens

Photographed along Mesquite Wash, Maricopa Co., Arizona. Aug. 1, 2009.

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ANNUAL: A common to abundant weed of disturbed soils at roadsides, in gardens, and along washes. Grows upright with few branches below. Plants growing to nearly 2 m tall are not uncommon.

RANGE: A cosmopolitan weed native to Eurasia and now found throughout North America. In the Sonoran Desert it is found in urban areas, agricultural margins and along riparian streams.

LEAVES: Margins of the leaves have sharp teeth and indentations. The teeth have prickles at the tip of each dentition. Milky sap from broken stems. More leaves are at base of plant and smaller leaves scattered up stems.

Prickly Lettuce, Lactuca serriola, photo © by Michael Plagens

Leaf of Prickly Lettuce seen near Pinetop, Arizona, Aug. 2009.

FLOWERS: Small, pale yellow, flower heads composed entirely of yellow strap-shaped florets flared out pin-wheel fashion. The florets open early morning in the desert and close before temperatures get too hot. The inflorescence stems are stiff and wirey and widely branched into a panicle. Flowering here late spring though fall.

FRUIT: The achene seeds bear a pappus of many fine capilary bristles at the top and have a beak at the top.

ARMED: The prickles can be surprisingly sharp.

Asteraceae -- Sunflower Family

More Information:

Sonoran Desert Field Guide
Sonoran Desert Places
Sonoran Desert Naturalist Home Page


Copyright Michael J. Plagens, 1999-2009