.= _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.

[Illustration: 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.

[Illustration: 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.

[Illustration: 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.

[Illustration: 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.

[Illustration: Fig. 194.]

=Fire-weed.= _Erechtites 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.

[Illustration: Fig. 195.]

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