CoioRADo Agricultural Colllgk 
1. Bur Thistle, Spear Thistle, 
Bull Thistle {Garduus lanceolatus 
L., Cirsium lanceolatum (L.) Hill.) 
(Fig. 145). — Seeds streaked with 
fine, broken, black lines, otherwise 
pale smoke-gray in color, 3.5-4 mm. 
long, 1.2-1. 5 mm. wide in the widest 
part, oblong, obscurely flattened, 
straight or slightly curved (bent), 
apex with a distinct knob-like pro- 
jection. 
2. Field Thistle {Garduus discolor 
{Muhl.) Nutt., Girsium discolor (Muhl.) 
Spreng.) (Fig. 146). — Seeds shiny, light 
Dresden-brown in color, with a circular band 
of light yellow at the apex ; seeds S.5-4.5 mm. 
long, 1.5-2 mm. wide in- the widest part, 
oblong, obscurely flattened, straight or 
slightly curved as in G. lanceolatum; apex 
vvith a knob-like projection. 
Fig-. 146. Field Thistlo 
.Cardiius discolor) x 12. 
3. Drooping Thistle, Flodman’s Thistle, {Garduus filipcndulus 
{hJngclm.) Xcis., (^irsirin flodmar-'' ^ thrlh.) Arthur) (Fig. 147). — Seeds 
shiny, brown in color, 5-7 mm. long, 1.5-2 
mm. wide in the widest part, oblong, 
obscurely flattened, mostly slightly curved, 
seldom straight; apex with a proportion- 
ately smaller knob-like projection than 
U. lanceolatum or G. discolor. 
4. Creeping Thistle, Canada Thistle 
{Garduus arvensis (L.) Rohs.) Girsium arvense 
{L.) Scop.) (Fig. 148). — Seeds shiny, buck- 
thorn-brown to Dresden-brown in color, 2.5-3 
mm. long, .7-1 mm. wide, slightly flattened, 
oblong, mostly straight, seldom curved; a])ex 
with a minute knob-like projection. 
(Curdiius iirven.sis). x 1;!. 
Fig. 148. Creeping Thistle 
Fig. 147. Drooping Thistle 
(Garduus flodmanii). x 7. 
