[Carduus vulgaris Savi; Cirsium arvensis sensu Hawaiian botanists, non (L.) Scop.; C. hawaiensis (H. Lev.) H. Lev.; C. lanceolatum sensu auct., non (L.) Hill; Cnicus hawaiensisH. Lev.]
(nat) Bull thistle, pua kala
Biennial herbs 5-15 dm tall; stems con-spicuously spiny-winged from the decurrent leaf bases, spreading hirsute to arachnoid pubescent. Leaves oblanceolate to elliptic, 10-20(-40) cm long, 3-8 cm wide, upper surface with pungent bristles, lower surface arachnoid pubescent to hirsute, coarsely toothed to irregularly pinnatifid, the larger lobes toothed or lobed, base decurrent for the whole internode or the upper ones less so. Heads several; involucre 2.5-4 cm high, 4 cm in diameter, sparsely arachnoid pubescent to woolly, the bracts spine-tipped, the spines 2-3.5 mm long; corollas purple, 26-36 mm long. Achenes 3-5 mm long. [2n = 56-60, 68, 102.] Native to Eurasia; in Hawaii naturalized in relatively dry to mesic areas on all of the main islands except Niihau. First collected on Hawaii in 1909 (Rock3315, BISH).—Plate20.