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, shining, 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.

long, shining, smooth or containing a few minute oppressed bristles, apex truncate, bearing a whorl of bristles, the longest having been rubbed off. Native of this country. Compare the above description with that of Erigeron annuus. Common in waste places.

[Ill.u.s.tration: Fig. 196.]

=Daisy Fleabane.= _Erigeron ramosus_ (Walt.) B. S. P. Flowers white; achenes nearly identical with those last described, Erigeron annuus, bristles shorter, less diverging, surface bearing more minute appressed hairs when seen under a lens. Native to this country and prominent in some thin meadows.

[Ill.u.s.tration: Fig. 197.]

=Sweet Everlasting.= _Gnaphalium polycephalum_ Michx. _Gnaphalium obtusifolium_ L. Outer scales of the head thin, white, stiff; achenes yellowish white or brown, slightly flattened, smooth, oval or oblong, .5-.7 mm. long. Native to this country. Not often troublesome.

Much practice with a good lens and careful comparisons with other small achenes will be necessary in identifying such specimens as are furnished by this species.

[Ill.u.s.tration: Fig. 198.]

=Low Cudweed.= _Gnaphalium uliginosum_ L. Outer scales of the head thin, brown, more or less wooly; achenes .4-.6 mm. long, yellowish white to brown, slightly flattened, smooth, narrowly oblong .4-.6 mm. long.

Achenes narrower and rather shorter than those of G. obtusifolium.

Native to this country. Not of high rank as a weed.

[Ill.u.s.tration: Fig. 199.]

=Broad-leaved Gum Plant.= _Grindelia squarrosa_ (Pursh.) Dunal. Flowers yellow; achenes creamy white or light brown, very variable in appearance, more or less flattened, often 4-angled, straight to much curved, narrowed at the base, apex truncate, often concave with a distinct marginal rim, some of them not very unlike those of Canada thistle, some of them smooth, others finely grooved or ridged lengthwise, others somewhat wrinkled, 2.5-3 mm. long. Occasionally introduced from the west with seeds of gra.s.ses or clover. Usually not persistent in Michigan.

=Artichoke.= _Helianthus tuberosus_ L. Flowers yellow; achenes black, shiny more or less, slightly flattened, p.u.b.escent with very short hairs, with four obtuse angles, narrowly obovate, 6-7 mm. long, one side of the smaller end projecting beyond the other side. Native of this country; cultivated by Indians.

[Ill.u.s.tration: Fig. 200.]

=Golden Mouse or Orange-Ear Hawkweed. Devil's Paint-Brush.= _Hieracium aurantiac.u.m._ Flowers orange yellow; achenes jet black, oblong, straight or curved, apex truncate, base abruptly tapering, cylindrical, the sides bearing 10 narrow, vertical ridges. Introduced from Europe. In Eastern New York and Western Ma.s.sachusetts meadows abound in large areas of this vile weed, 1.8-2.2 mm. long.

[Ill.u.s.tration: Fig. 201.]

=Mouse-Ear Hawkweed.= _Hieracium Pilosella_ L. Flowers yellow; achenes jet black, oblong, straight or curved, apex truncate, base abruptly pointed, cylindrical or narrowly oval, the sides bearing 10 narrow vertical ridges. Introduced from Europe. The achenes very closely resemble those of the orange hawkweed. It doesn't matter much, for the habits are the same, and one is about as noxious as the other.

Introduced from Europe.

[Ill.u.s.tration: Fig. 202.]

=Elecampane.= _Inula Helenium_ L. Flowers yellow; achenes light brown, straight or curved, linear, flattened, 4-5 mm. long, 4 sided with 5-8 obscure vertical ridges on each side, apex concave, the margin bearing a circle of short stiff bristles, the remains of longer ones. Introduced from Europe. Not common.

[Ill.u.s.tration: Fig. 203.]

=Marsh Elder.= _Iva xanthiifolia_ (Fresen.) Nutt. Achenes various shades of brown to black, flattened or rhombic in section, obovoid, 1.5-2 mm.

long, longitudinally, striate with fine lines. Native to the upper peninsula of Michigan where it most likely was at one time introduced from the west. It has not been found in the lower peninsula, probably because it had no means of coming across Lake Michigan.

[Ill.u.s.tration: Fig. 204.]

=Wild Lettuce.= _Lactuca Canadensis_ L. Flowers yellow; achenes black or nearly so, flattened, oval, bearing 3 ribs, the lateral ones sometimes double, the middle one slender, surface abounding in minute transverse ridges as seen under a lens, the remains of a beak sometimes remaining.

Native of this country. Other species of Lettuce are more or less troublesome.