PlantFiles: Canada Lettuce, Tall Lettuce, Tall Wild Lettuce
Lactuca canadensis

The following information is from The Encyclopedia of Edible Plants of North America by Francois Couplan Ph.D. (Note: This information applies to all Wild Lettuces of the Lactuca genus.)

"Lettuce contains vitamins A, B1, B2, C, D, and E, minerals, a bitter principal, and various substances, including a very large proportion of water for cultivated specimens: up to 96% in certain "iceberg" types, notwithstanding the chemical residues found in commercially grown plants.

The plant is soothing, emollient, laxative, depurative, and refrigerant.

The latex of cultivated plants when they go to seed, or especially of wild lettuce (especially L. virosa - naturalized from Eurasia in California), yields a dark brown, very bitter substance after drying known as "lactucarium," which has antispasmodic, sedative, and hypnotic properties. It has been used medicinally like opium, the dried latex of the opium poppy (Papaver somniferum, Papaveraceae), with good results in certain cases. Moreover, lactucarium has no toxicity. It has even been used as a substitute to cure opium addiction.

The juicy pith within the stems of flowering lettuce is delicious to eat raw after peeling the outer rind of the stem. Some varieties, known as "celtuce," are now grown specifically for this purpose in North America.

Garden lettuce has been cultivated since Antiquity.

The very young shoots and leaves, light green and tender, of the various species of wild lettuce are delicious raw in salads. Older leaves may be cooked in several waters to eliminate their bitterness.

The inflorescences are edible as well."

The following information is from Edible Wild Plants: Eastern / Central North America by Lee Allen Peterson.

"Use: Salad, cooked green, cooked vegetable. Although somewhat bitter, the young leaves can be added fresh to salads or boiled 10-15 minutes in 1 change of water and served with butter or vinegar. The cooked leaves still leave a slightly bitter aftertaste and are best mixed with other greens. The developing flowerheads, before the stems unfold and the flowers bloom, impart a unique bitter flavor when added to casseroles."

American Indians used plant tea as a mild sedative, nerve tonic and pain reliever. Milky latex from the stem was used on warts, pimples poison ivy rash and other skin irritations.

The small flowers attract bees primarily, such as Megachile latimanus (Large Leaf-Cutting Bee sp.). Goldfinches occasionally eat the seeds. Notwithstanding the bitter white latex in the foliage, mammalian herbivores occasionally eat this plant. The Cottontail Rabbit eats the tender leaves of first-year plants, while the White-Tailed Deer eats the tops off of more mature plants. Horses are reportedly very fond of this plant.