Part 12 (1/2)

Flowers purple; achenes dull brown, often spotted with black, straight or curved, slightly flattened, oblong-prismatic with 3-5 narrowly ridged angles, and occasionally other smaller ridges, 4.5-6 mm. long.

Introduced from Europe.

[Ill.u.s.tration: Fig. 184.]

=Biennial Wormwood.= _Artemisia biennis_ Willd. Achenes dark brown, smooth, somewhat flattened, 3-4 angled, obovate, narrowed at the base .8-1.3 mm. long. Native in the northwestern United States and introduced east with gra.s.s seeds. Moist land.

[Ill.u.s.tration: Fig. 185.]

=Smaller Bur-Marigold.= _Bidens cernua_ L. Flowers yellow; achenes 4-6 mm. long, dull brown, the awns lighter, flattened, 4-angled, wedge-shaped, awns 2-4, barbed downward as also are the ribs. Native of this country. Low lands.

[Ill.u.s.tration: Fig. 186.]

=Purple-stemmed Swamp Beggar-ticks.= _Bidens connata_ Muhl. Flowers orange; achenes brown, wedge-shaped or obovate, hairy, tubercled, flattened, 4-angled, 4-toothed, 4-6 mm. long, achenes and teeth downwardly barbed. Swamps, common.

[Ill.u.s.tration: Fig. 187.]

=Beggar-ticks.= _Bidens frondosa_ L. Achenes dull brown, tubercled, much flattened, obovate or oval, 6-12 mm. long, awns usually 2, spreading barbed downward. Low lands.

[Ill.u.s.tration: Fig. 188.]

=Star Thistle.= _Centaurea solst.i.tialis_ L. Achene cream white to mottled brown, flattened, oval about 2 mm. long; scar of attachment in a notch of one edge above the rounded base, apex truncate with a small tubercle in the middle. Found in seeds of alfalfa. A ragged plant from Europe.

[Ill.u.s.tration: Fig. 189.]

=Ox-eye Daisy.= _Chrysanthemum Leucanthemum_ L. Flowers white; achenes brown or black with ten white conspicuous vertical ribs, narrowly obovate 1.5-1.8 mm. long, bearing a tubercle at the apex. Introduced from Europe. Becoming common. A prominent weed in old pastures and meadows.

[Ill.u.s.tration: Fig. 190.]

=Chickory.= _Chichorium Intybus_ L. Flowers yellow; achenes light brown, more or less mottled or spotted with black, straight or curved, 4-5 angled, flattened, apex truncate crowned with a double row of minute scales. Achenes 2.5-3 mm. long. Introduced from Europe.

[Ill.u.s.tration: Fig. 191.]

=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.

[Ill.u.s.tration: Fig. 192.]

=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.

[Ill.u.s.tration: Fig. 193.]

=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.

[Ill.u.s.tration: Fig. 194.]

=Fire-weed.= _Erecht.i.tes hieracifolia_ (L.) Raf. Achenes brown, linear, 2.2-2.8 mm. long, flattened, straight or curved, having ten vertical ribs between which are minute white oppressed hairs, the extremities truncate, wider than the narrow portion beneath, the apex white with a tubercle projecting from the center of a minute cup. Native to this country. Not of much importance.

=Annual Fleabane.= _Erigeron annuus_ (L.) Pers. Flowers white; achenes smooth, s.h.i.+ning, brownish white, translucent, flattened, obovate or oblong, .7-.9 mm. long, bearing at the apex a whorl of very small diverging bristles, the longest ones having been rubbed off. Faint traces of a few oppressed hairs may be seen under a good lens. Native to this country and a very prominent weed in thin meadows.

[Ill.u.s.tration: Fig. 195.]

=Horse-weed.= _Erigeron Canadensis_ L. _Leptilon Canadense_ (L.) Britton. Achenes oblong, dull cream color, much flattened, 1-1.3 mm.