=Corn Sow-Thistles.= _Sonchus arvensis_ L. Flowers yellow; achenes dull, dark reddish brown, oblong, extremities blunt, slightly flattened, bearing four coarse, fold-like ridges, with two smaller ridges between each of the two large ones, transversely wrinkled, 2.5-3 mm. long. This species is a perennial spreading by roots-stalks as well as by seeds. Introduced in Europe. [Illustration: Fig. 209.] =Spiny Sow-Thistle.= _Sonchus asper_ (L.) Hill. Flowers pale yellow; achenes dull straw-color to reddish brown, much flattened, obovate, oblong, extremities blunt, each side bearing 3-5 vertical ridges, surface nearly smooth, 2.5-3 mm. long. Introduced from Europe. [Illustration: Fig. 210.] =Common Sow-Thistle.= _Sonchus oleraceus_ L. Flowers pale yellow; achenes reddish brown, linear, oblanceolate, 3 mm. long, flattened extremities blunt, 5 uneven wrinkled ridges on each side. Introduced from Europe. [Illustration: Fig. 211.] =Red-Seeded Dandelion.= _Taraxacum erythrospermum_ Andrz. Achene bright red or red reddish brown, flattened, oblanceolate, 3 mm. long, 1 mm. wide or less, the red beak 1 mm. long, prickles often extending nearly to the base along twelve vertical ribs, the achenes narrower, shorter, much darker in color, with prickles extending farther down the ribs, the short beak longer; the plant is earlier, often smaller, when compared with the other species. Doubtless this is more common than has been reported, having been overlooked. Introduced from Europe. [Illustration: Fig. 212.] =Dandelion.= _Taraxacum officinale_ Weber. _Taraxacum Taraxacum_ (L.) Karst. Flowers yellow; achenes dull light to dark brown, flattened oblanceolate, thread-like beak two to three times as long as the achene, the stout colored beak 0.5 mm. long. The most conspicuous character of the achenes lies in the barb-like-toothed edges and ridges of each of the similar faces, extending along the upper half. Achene, 3-4 mm. long, having twelve longitudinal ridges, 1.2 mm. wide. Introduced from Europe. Troublesome on thin lawns. [Illustration: Fig. 213.] =Salsify. Oyster-Plant.= _Tragopogon porrifolius_ L. Flowers purple; achenes dull light brown, nearly cylindrical; apex tapering, mostly terminating in a slender beak which is often longer than the body of the achene. Achene straight or curved, 10-ribbed, 12-18 mm. long, outermost coarsely roughened by upwardly directed, whitish, scale-like projections. Native of Europe. =Meadow Salsify. Yellow Goat's Beard.= _Tragopogon pratensis_ L. Flowers yellow; achenes dull, light brown, nearly cylindrical, apex tapering, mostly terminating in a slender beak. Achene straight or curved, 10-ribbed, 12-15 mm. long, the inner ones of the head smooth, the outer-most coarsely roughened by upwardly directed, whitish, scale-like projections. Introduced from Europe. [Illustration: Fig. 214.]