Annual, to 150 cm. Stems widely branched, glabrous. Leaves linear, ilnear-elliptic or narrowly oblong, to 15 x 2 cm, with sparsely serrate, setose margins. Capitula 5-8 mm. Phyllaries imbricate, acuminate, green with purplish tips, with hyaline or scarious margins. Ray florets purple, blue or whitish, ± longer than phyllaries but small and inconspicuous, becoming circinnately rolled outwards. Disc florets yellowish, fewer and smaller than ray florets. Achenes hairy. Fl. 8-10. Roadsides and salt marshes. nr s.l.
N. American alien.