Colorado Agricultural College 
sive space for enumeration. 
It IS not to be expected, neither is it essential, that a dealer 
in, or a buyer of, seeds know the number of different sorts of 
weed seed species that have been found in crop seeds, but it is 
of value to be able to recognize those weed seeds which occur 
most frequently or are particularly harmful. Por example, the 
seeds of wild oats, bindweed, wild buckwheat, and cow cockle 
occur more commonly in wheat and are more harmful and undesir- 
able than the seeds of slender wheat grass or bee plant. A knowl- 
edge of the nature of the impurities, then, is of more importance 
to the purchaser than a statement of the amount (percentum) of 
the impurities present. For example, one lot of alfalfa seed, 99:2 
per cent, pure, contains dodder and wild mustard, another lot, 95 
per cent, pure, contains no harmful or undesirable weed seeds, and 
though inferior in purity to the preceeding lot is of superior qual- 
ity because of the nature rather than amount of the impurities 
present. Seed of high purity and free from harmful weeds is the 
most desirable, being an improvement over either of the above 
possibilities. It is necessary, then, that care be exercised in the 
selection of all seed though the foregoing cannot be accomplished 
without a knowledge of what makes for better seed, together with 
a desire to improve seed quality. 
The keys, descriptions, and drawings, included in this bulletin 
were made that they might be of some assistance in supplying the 
need for information which is helpful in both buying and selling 
seeds, particularl}^ field seeds ; also that they might be of use for 
reference or classwork in schools. 
The noxious weed seeds designated in the Colorado Seed Act, 
appear on page 21. Any of these seeds are considered particularly 
harmful. 
It is unnecessary to devote more than a few words to the often 
quoted and usually misunderstood term “adulteration”. In the 
past seed merchants “adulterated” the seeds they were selling by 
taxing with them seeds of other species. Thus wild musbard 
s^ds, the germs killed by drying in an oven, were mixed with 
cabbL^e, turnip or cauliflower seeds and sold as such. Today 
adulteration” has a different meaning, is practiced in a far dif- 
ferent \\,y, and is not readily detected. Old seeds that have lieen 
