Prickly Lettuce. Lactuca virosa L. For many years erroneously called Lactuca scariola. Flowers yellow; achenes dull, dark brown, mottled with black, flattened, bearing 5–7 rough, vertical ridges, interspersed by as many smaller ones; oblong, obovate, widest toward the tapering apex. 3–3.5 mm. long. Some of the leaves turn one edge up and the other down. Introduced from Europe and has proved itself a remarkable traveller.

Fig 206. [Fall Dandelion. Leontodon autumnalis] L.

Fall Dandelion. Leontodon autumnalis L. Flowers yellow; achenes light brown, linear, with 5 broad, rounded ribs; achene 4–6.5 mm. long, straight or curved, the outer traversed, with low transverse ridges. Introduced from Europe.

Fig 207. [Black-eyed Susan. Yellow Daisy. Rudbeckia hirta] L.

Black-eyed Susan. Yellow Daisy. Rudbeckia hirta L. Achene purple-brown to black, slightly tapering from base to apex 1.5–1.8 mm. long, base abruptly pointed, apex truncate, in cross section nearly square, having 5–7 slender vertical ridges on each side besides a larger one at each of the four corners. Widely distributed in meadows and pastures.