Fig 191. [Canada Thistle. Cirsium arvense] (L.) Scop. Carduus arvensis (L.) Robs.

Canada Thistle. Cirsium arvense (L.) Scop. Carduus arvensis (L.) Robs. Flowers purple or white; achenes smooth, light brown, curved or straight, narrowly obovoid or oblong, slightly flattened, 2–3 mm. long, apex truncate, cup-shaped with a tubercle in the center. Introduced from Europe. A weed of first rank.

Fig 192. [Bull Thistle. Cirsium lanceolatum] (L.) Hill. Carduus lanceolatus L.

Bull Thistle. Cirsium lanceolatum (L.) Hill. Carduus lanceolatus L. Flowers purple; achenes smooth, nearly white, with sharp vertical brown stripes, slightly flattened, obovate or oblong, usually curved near the apex, 3–4 mm. long, apex truncate with a large tubercle in the center. Introduced from Europe.

Fig 193. [Narrow leaved Hawksbeard. Crepis tectorum] L.

Narrow leaved Hawksbeard. Crepis tectorum L. Flowers yellow; achene chestnut brown, straight or curved, linear, ribs 10, smooth or rugose; 3.4 mm. long. Introduced from Europe.