Lactuca tatarica

Lactuca tatarica (L.) C. A. Mey.
Engl.: blue lettuce, blue-flowered lettuce, common blue lettuce, perennial lettuce, showy lettuce, Siberian sow-thistle.
Fran.: laitue bleue.
Bot. syn.: Lactuca oblongifolia Nutt., Lactuca pulchella (Pursh) DC., Sonchus tataricus L.