Colorado Experiment Station 
() 
Plate II — Map showing distribution of Perennial Peppergrass in Colorado. Shaded 
areas indicate localities from which it has been reported. 
Luis Valley Avhere in many instances entire alfalfa fields have been 
invaded. ^ 
V. Methods of Dissemination — Considering the habits of this 
plant it is almost certain that in time it will spread over most of the 
state unless effective control measures are used. Its large, white, 
perennial, underground root stock, which in some instances pene- 
trates the soil several feet and spreads horizontally in all directions, 
enables it to spread out from year to year. The writers have seen 
patches in alfalfa fields which have been invaded by this weed where 
the alfalfa plants have been completely crowded out and a hundred 
per cent stand of this pernicious pest has taken its place. Not only ^ 
does it spread over fields in this way Avhere it has gained a foothold 
but it is quite freciuently introduced into new localities by the dis- j' - 
semination of its seeds in foul alfalfa. The size of the seed is quite ^ 
similar to that of alfalfa and unless purity tests have been made ()f J 
such seed it is very apt to esca])e the attention of the })ui‘chasei*. 1 be 
Colorado Seed Laboratory received, during the past year, nine lots 
of alfalfa and sweet clover seeds which contained this inii>uri1y. 
Light of these samples were native grown. 
