ye ee _ ee ea ee ee ee eee ee ee ee eee ee Se ee ye 
KUROPEAN PLANTS GROWING WITHOUT 
CULTIVATION IN COLORADO 
BY 
FRANCIS RAMALEY 
Professor in the University of Colorado. 
Geographical position of Colorado. Colorado is one of the Rocky 
Mountain States of North America situated in the high interior 
of the continent between 37° and 41° north-latitude and 102° 
and 109° longitude west of Greenwich. About two-thirds of the 
area has a drainage to the Mississippi River-system and the 
remaining one-third, through tributaries of the Colorado River, 
drains to the Gulf of California. The continental divide extends 
in a zig-zag course from north to south through the state, following 
for the most part the highest points of the main range of the 
Rocky Mountains. Colorado has an area of about 100.000 square 
miles or almost exactly one-half that of France. 
Physiography and climate. The eastern part of the state is a 
plain which slopes away gently from the base of the mountains. 
Mountains and foothills occupy the central part of the state, 
while to the west is a high plateau dissected by stream erosion 
and having numerous considerable elevations. The annual rain- 
fall is less than 20 inches, except in higher mountain districts, 
hence mesophytic species are to be found only in artificially 
irrigated tracts or in seepage areas along streams, ponds ete. 
Temperatures are generally favorable for the growth of plants 
accustomed to a temperate climate, the mean annual tempe- 
rature at Denver being 49°.8 F. (9°.9 C.) In that part of the 
plains-region which is under cultivation, all of the ordinary 
cereals are grown, such as wheat, oats, rye and barley as also 
