Part 13 (1/2)

[Ill.u.s.tration: Fig. 205.]

=p.r.i.c.kly 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.

[Ill.u.s.tration: Fig. 206.]

=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.

[Ill.u.s.tration: Fig. 207.]

=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.

[Ill.u.s.tration: Fig. 208.]

=Corn Sow-Thistles.= _Sonchus arvensis_ L. Flowers yellow; achenes dull, dark reddish brown, oblong, extremities blunt, slightly flattened, bearing four coa.r.s.e, 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.

[Ill.u.s.tration: 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.

[Ill.u.s.tration: 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.

[Ill.u.s.tration: Fig. 211.]

=Red-Seeded Dandelion.= _Taraxac.u.m erythrospermum_ Andrz. Achene bright red or red reddish brown, flattened, oblanceolate, 3 mm. long, 1 mm.