Colorado Weed Seeds 
13 
in storage for years, or seeds that have been carried over for one 
or two years, seeds of low vitality, and mechanically injured seeds, 
all may be mixed proportionately with seeds of the same species 
having a high germinating power. For example, 50 pounds of 
Danish ball head cabbage having a vitality of 40 per cent, when 
mixed thoroughly with 200 pounds of the same variety with a 
vitality of 95 per cent, would give 250 pounds of cabbage with an 
average vitality of 84 per cent. 
A better understanding of the common impurities and adulter- 
ants has created greater interest in better seed, and with it the 
realization that the best seed is the cheapest after one considers 
not the initial cost of inferior seed but its damaging effect upon 
clean fields. Seed may be pure and of good germination but low 
in quality because of its color. Though color alone should not 
regulate quality and seed values it is a valuable indicator in that 
it shows careful harvesting, good hulling, and allows ready detec- 
tion of foreign seeds. 
In buying seed one should keep in mind the following points : 
Purity, amount and nature of impurities, germination, source of 
seed, and color. If buying from your neighbor, keep in mind the 
above points and in addition ask yourself whether or not the seed 
can be further cleaned by sieves or milling machinery for, though 
seed companies’ stocks are usually cleaned by special machinery 
your neighbor has no such equipment, neither does he realize the 
amount and nature of the impurities that may be removed from 
average lots of seed by even a hand sieve or a small hand mill. 
purity analysis is easily made when there are drawings or 
samples of weed seeds at hand for comparison. This entire bul- 
letin may be looked thru for a drawing of the seed to be determ- 
ined, or more easily by first referring to the family key on page 3. 
After finding the family to which the seed belongs, do the same 
for the genus and species by referring to the respective keys. 
Figures 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, and 164 were drawn by 
the author, and the remainder are the work of Miss Caroline M. 
Preston. 
'Colo. Agri. College Bull. 238, “Cleaned. Treated, and Tested Seed’’. 
