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Lactuca serriola L.

Prickly lettuce

KingdomPlantaePlants, but not fungi, lichens, or algae
SubkingdomTracheobiontaVascular plants—plants with a “circulatory system” for delivering water and nutrients
DivisionMagnoliophytaFlowering plants, also known as angiosperms
ClassMagnoliopsidaDicotyledons—plants with two initial seed leaves
SubclassAsteridaeA large class that encompasses asters
OrderAsteralesFlowering plants with a central disk flower and surrounding petals, like daisies
FamilyAsteraceaeThe aster family, which also includes daisies and sunflowers; from the Greek ἀστήρ, “star,” for the star-shaped flowers
GenusLactucaFrom lacta, Latin for “milk,” referring to the milky sap in stem, and a root word for lactic acid
SpeciesserriolaEither in ranks, or pertaining to salad, being one form of an old name for chicory

About plant names...

Prickly lettuce originated in the Mediterranean uplands in Europe. It is now widely distributed in parts of Europe, Asia, Africa, and North America.

Identification: Plants are erect, 12-79″ (30-200 cm) tall. Stems sometimes have stiff hairs near the bottom; stems and leaves have a milky sap when cut. Leaves are alternate, 1¾-12″ (5-30 cm) long and ⅜-4″ (1-10 cm) wide. The mid-ribs of leaves have prickers along the bottom. Typically leaves are deeply lobed. Panicles form open, roughly conical clusters of flowers. Flowers are ⅜-½″ (1-1.5 cm) in diameter, and have 13-27 florets (petals) each. Flowers appear July-September. Fruits are ⅛″ (3 mm) long, single-seeded, lance-shaped, attached to a "parachute" like dandelions.

Some Lactuca species:

 

Lactuca serriola (prickly lettuce)

9/25/2009 · Nashua River Rail Trail, near Hospital, Ayer, Mass­a­chu­setts ID is uncertain

Lactuca serriola (prickly lettuce)

7/31/2016 · Skyline Drive, Shenandoah National Park, Virginia

 
Lactuca biennis

Lactuca canadensis
You are here
Lactuca serriola
Common Name

tall blue lettuce

wild lettuce

prickly lettuce
Plant Tall blue lettuce grows up to 6′ (1.8 m) high. 4-10′ (1.2-3 m) tall, with stems that are green or spotted with purple. The latex from a broken stem is brown. Erect, 12-79″ (30-200 cm) tall. Stems sometimes have stiff hairs near the bottom; stems and leaves have a milky sap when cut.
Flowers Blue, about ¼-½″ (6.3-12 mm) across, in crowded clusters at the top. At the top, large cone-shaped panicles consisting of 50-100 flowers appear. Individual flowers are about ¼″ (8.5 mm) around, with 15-22 florets (tiny petals) each. They are yellow, pinkish-orange, or reddish. In panicles that form open, roughly conical clusters of flowers. Flowers are ⅜-½″ (1-1.5 cm) in diameter, and have 13-27 florets (petals) each. Flowers appear July-September.
Leaves Leaves are deeply divided, like those of dandelions, but while dandelion leaves are roughly the same width along their length, these are more triangular in overall shape. They are up to 1′ (30 cm) long and 6″ (15 cm) wide at the base, tapering to sharp tips. Leaves are hairy, undersides more so. Vary greatly in shape, and may resemble the shape of a sickle, or long and narrow, or wider and deep lobes. They are 6-14″ (15-35 cm) long. Alternate, 1¾-12″ (5-30 cm) long and ⅜-4″ (1-10 cm) wide. The mid-ribs of leaves have prickers along the bottom. Typically leaves are deeply lobed.
Fruit   Achenes (seeds) are small and brown, each with a "parachute" attached, like dandelions. ⅛″ (3 mm) long, single-seeded, lance-shaped, attached to a "parachute" like dandelions.
Range/ Zones

Habitats Redwood forest, wetlands Woodland margins, clearings, near the edges of water, roadsides, pastures. Grasslands, seasonal wetlands, orchards, vineyards, urban places, roadsides, disturbed habitats.
Type Wild Wild Wild
Occurrence Common Common Common

 

Edibility/medicinal: Prickly lettuce is a wild progenitor of the common lettuce varieties that we eat (Lactuca sativa), but it contains compounds that make it taste bitter. It also contains a compound that is a mild soporific; in the past, "Syrup of Lactucarium" was a commercial product sold to help with bronchitis, the flu, colds, coughs, asthma, etc. Its effects have been compared to those of opium, though much milder, hence the term "lettuce opium." Whether these effects even exist is debatable—in 1893, it was described as a "feeble narcotic."

Online References:

Southeastern Arizona Wildflowers and the Plants of the Sonoran Desert

The Virginia Tech Weed Identification Guide

Montana Plant Life

Illinois Wildflowers

Drugs-Forum

Vascular Plants of the Gila Wilderness

CalPhotos

Plants for a Future, a resource and information centre for edible and otherwise useful plants

Vascular Plants of the Gila Wilderness

The Jepson Manual

Lactuca serriola (prickly lettuce)

7/31/2016 · Skyline Drive, Shenandoah National Park, Virginia

Lactuca serriola (prickly lettuce)

8/4/2010 · Nashua River Rail Trail, Groton Center, Groton, Mass­a­chu­setts · ≈ 1 × 1½′ (34 × 52 cm) ID is uncertain

Lactuca scariola L.

 

Lactuca serriola description by Thomas H. Kent, last updated 6 May 2023.

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Lactuca serriola (prickly lettuce)

7/31/2016 · Skyline Drive, Shenandoah National Park, Virginia

Lactuca serriola (prickly lettuce)

8/29/2014 · Along Rio Grande gorge, New Mex­ico · ≈ 10 × 7″ (25 × 16 cm)

Range:

About this map...