IIO A Study of the Vegetation of 
the fall of the year and tumbling over the ground, is piled by the 
wind into great heaps on the leeward slopes of the hills. 
Westward, in the drier regions, and especially in the scab-lands, 
Sisymbrium altissimum, locally known as Jim Hill mustard, from 
its introduction along the right of way of the railroads, is pres- 
ent to a degree almost unbelievable. Hundreds of acres in the 
scab-lands are literally “taken” by this weed. From dwarfed 
specimens a few centimeters high on the scab-rock, it ranges to 
rank growths in the moist soil. It is a bad weed in the wheat 
fields throughout the greater part of the region. 
The tar weed, Amsinckia intermedia, is likewise a troublesome 
weed along roadsides and especially in wheat fields. South of 
Snake River it is very abundant. Its dense coat of long bristly 
hairs upon drying becomes extremely annoying to both men and 
horses. 
Westward and especially in the slightly alkali regions the Rus- 
sian thistle, Salsola kali tenuifolia, and the Australian salt bush, 
Atriplex semibaccata, are often abundant. 
Dipsacus sylvestris, introduced a number of years ago, has 
spread very rapidly and in many localities assumes the role of a 
very thrifty and very obnoxious weed. 
The little geranium, Erodium cicutarium, is an introduced 
weed which has become very common in gardens, feed lots, and 
waste places. Often associated with it are Sanguisorba annua, 
Geranium pusillum, and Verbascum thapsus. 
Common roadside weeds of especial abundance are Madia 
glomerata, Marrubium vulgare, and the rattle grass, Bromus 
brizaeformis. The absence of most roadside weeds so common in 
the eastern and central states is very characteristic. 
About the numerous grain-loading stations throughout the 
region many ruderals are gaining a foothold. Here the cars are © 
swept out and the seeds of various plant species scattered. 
Among other weeds thus recently introduced, and which I have 
seldom seen elsewhere, may be mentioned Ambrosia trifida, A. 
psilostachya, Melilotus alba, M. officinalis, Cirsium arvense, Iva 
xanthifolia, Datura tatula, and Datura stramonium. The prob- 
lem of grain warehouses as centers of weed distribution would 
IIO 
