28 THE MONTANA EXPERIMENT STATION. 



in waste places, where it shows a strong disposition to spread 

 and become troublesome to the sheep industry. 



13. *ARENARIA SERPYLLIFOLIA, L. 



A small, inconspicuous annual two or three inches high, or 

 prostrate, of European origin, well established about the streets 

 and waste places at Columbia Fails, but not otherwise noted in 

 the state. 



14. ARTEHISIA BIENNIS, Willd. Wormwood; Ironweed. 



An annual or biennial coming in from the west, two or three 

 feet high, with a slender, reddish stem, finely divided leaves and a 

 narrow terminal spike-like panicle of inconspicuous flowers. Be- 

 coming common in streets and waste places about the larger 

 towns and thence spreading to the highwa} r s and neighboring 

 fields, where it is beginning to be a troublesome pest. 



15. ARTEMISIA LUDOVICIANA, Nutt. White Sage. 



A native perennial sage with long creeping rootstocks which 

 tend to persist in new ground and meadows and is often difficult 

 to eradicate. 



16. *ATRIPLEX HORTENSIS, L, Orache. 



Escaped from cultivation, particularly the ornamental variety 

 atrosanguinea, Hort. Not infrequent in yards and waste places 

 about Helena and Bozeman,but not likely to become troublesome. 

 An annual much resembling its relative the Lamb's-quarter. 



17. ATRIPLEX PATULA HASTATA, Gray. 



An annual much resembling and often confused with Lamb's 

 Quarter; occurring along streets and in waste places; apparently 

 introduced from the East. Occurs occasionally in nearly every 

 part of the state but is rarely troublesome in cultivated ground. 



18. AVENA FATUA, L. Wild Oats. 



This is one of the most common, if not the worst weed in the 

 state. Introduced from the Old World, but now common through- 

 out most parts of arid America where oats have been cultivated. 

 The wild oat differs from the cultivated variety in its usual ranker 

 growth, deeper color of the foliage, more diffuse panicle, earlier 



