Blue lettuce

Lactuca tatarica, blue lettuce or Russian wild lettuce, is a rhizomatous perennial herb in the Asteraceae reaching 30 to 80 cm tall, with erect, glabrous, glaucous stems exuding white latex when broken. Lower leaves are oblanceolate to lanceolate, 5 to 15 cm long, entire to pinnatifid with backward-pointing lobes and a clasping base; upper leaves become smaller and entire. The inflorescence is an open, paniculate cyme of ligulate heads, each 15 to 25 mm across with 18 to 50 pale blue to lavender ray florets and no disc florets, blooming midsummer through early autumn. Achenes are flattened, ribbed, dark brown, and bear a white pappus of fine bristles. The species occupies saline meadows, riverbanks, alkaline flats, sandy shores, and disturbed roadsides across the western United States, Canada, and Eurasia, spreading aggressively from deep, brittle rhizomes.