WEEDS OF MONTANA. 17 



Euphorbia glyptosperma, Engeltn "Spurge." 



Gaura coccinea, Nutt 



Helianthus aniuius. L "Sunflower. ' 



Iva xanthiifolia, Nutt "Horscweed." 



Lactuca pulchella, DC " M ilkweed." 



Rumex Acetosella, L "Sheep Sorrel." 



Polygonum Convolvulus, L "Wild Buckwheat." 



Saponaria Vaccaria, L "Cockle." 



II. PRACTICAL CONSIDERATIONS. 



riETHOD OF ERADICATION. 



1. Crop Rotation — It will be seen from the foregoing lists 

 that our weeds, troublesome in cultivation, tall naturally into 

 three groups: (1) weeds of grain fields, (2) of meadows and (3) of 

 cultivated ground and that our yards, roadsides and waste 

 places are the chief sources of local infection. The natural method 

 for the suppression of weeds then must be by crop rotation, as the 

 growth of one kind of crops tends to restrain or destroy the weeds 

 peculiar to the other two groups. Therefore, when our grain fields 

 become foul with the sunflower or wild oats, they should be put in 

 timothy, alfalfa or clover till the weeds have been crowded out; or 

 the land may be cultivated in some root crop like potatoes, ruta- 

 bagas, &c, and the weeds destroyed by frequent cultivation. 

 Unfortunately, here in Montana, the climatic conditions limit this 

 crop rotation almost to cereals and hay -lands, as maize can be 

 grown profitably in but few parts of the state and root crops and 

 garden truck can not be planted over any great area, on account 

 of the expense and labor involved and the certainty of swamping 

 the market. 



