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142 ILLINOIS ACADEMY OF SCIENCE 
to 4mm. long. If there has been thrashing, the outer covering 
may have been removed, exposing the achene. It is seal brown, 
the surface polished, ovoid, a large tubercle at the base; 2.5 
mm. long and 1.5 to 1.8 mm. in diameter. Common impurity 
of red clover, wheat, barley and grass seed. Plate ILI. 
ANTHEMIS CoTuLa. Dog-fennel. Mayweed.  Dillweed. 
Achene brownish, obovoid, the surface warty ribbed, a tubercle 
projecting from the apex; 1.5 to 1.5 mm. long. Common im-. 
purity of red clover, timothy, blue grass and alfalfa seed. 
Plate IV. 
CIRSIUM LANCEOLATUM. (Carduus lanceolatus.) Common 
thistle. Bull thistle. Burr or spear thistle. Achene straw 
colored, slightly flattened, the surface marked by vertical 
stripes, a large tubercle in the center of a cup-like apex; 4 to 
5 mm. long and 1 to 1.5 mm. in diameter. Common impurity 
in clover, alfalfa and grass seed. Plate IV. ) 
CirsiuM arvensE. (Carduus arvensis.) Canada thistle. 
Creeping thistle. Achene tan color, obovoid, to oblong, cup- 
shaped at apex with a small tubercle in the center of it; 3 to 3.5 
mm. long and .7 to 1 mm. in diameter. Common impurity of 
clover, alfalfa and grass seed. Plate V. 
Lactuca scarioua. Prickly lettuce. Compass plant. Achene 
brownish, obovate with many black-spotted vertical ridges, 
widest towards the tapering apex; 3 to 3.5 mm. long. In grass 
seed. Plate IV. 
-CrcuHorium Inrysus. Chicory. Blue sailors. Wild succory. 
Bunk. Achene light brown, often curved, the apex truncate 
and crowned with two rows of scales; 2.5 to 3 mm. long and .8 
to 1mm. in diameter. Common impurity of red clover and 
alfalfa seed. Plate III. 
BIBLIOGRAPHY 
Beal, W. J. The Seeds of Michigan Weeds. Bull. 260, Michi-— 
gan Agricultural College Experiment Station, 1910. East 
Lansing, Michigan. 
Blatchley, W. S. The Indiana Weed Book. Nature Publishing 
Company, Indianapolis, Indiana. 
