60 THE MONTANA EXPERIMENT STATION. 



116. SOLANUM ROSTRATUM, Dunal. Buffalo Bur. 

 A prostrate annual, with yellow flowers and a bur-like fruit, 

 thickly covered with long, yellow spines. Coming into the state 

 from the east along the railway's and becoming troublesome in 

 yards, waste places and cultivated ground. At various points 

 along the Yellowstone, Missoula, Box Elder Creek, Glasgow and 

 Culbertson. It should be killed out in all localities before it be- 

 comes a pest. It spreads slowly, but holds well where established. 



117. SOLANIUM TRIFLORUM, Nutt. Wild Tomato; Stixkweed. 

 A prostrate spreading annual with lobed leaves, small white 



or pale blue flowers and numerous green, many seeded berries. 

 Frequent in gardens, waste places and cultivated ground through- 

 out much of the region east of the Divide. The host of the Colo- 

 rado potato beetle. Doubtfully native. [Fig. 18]. 



118. SONCHUS ASPER, Vill. Sow Thistle; Yellow Thistle. 



A thistle-like annual with spiny clasping leaves and yellow 

 flowers; two or three feet tall. Introduced from Europe by way 

 of the eastern states and now frequent and often troublesome in 

 gardens and cultivated ground, particularly about Bozeman and 

 Kalispell. Seeds feathery and scattered by the wind. 



119. *SONCHUS OLERACEUS, L. 

 Very similar to the last and commonly not distinguished from 

 it. It is more slender, less prickly and has cross-ribbed seeds. It 

 occurs with the other species, but is far less frequent. 



120. *SPERGULA ARVENSIS, L. Field Spurry. 

 An annual introduced from the Old World with slender, 

 branching stems and numerous clusters of thread-like leaves. In 

 main fields at Bozeman but not elsewhere noted. 



121. 'STELLARIA MEDIA, Smith, Chickwkkd. 



A small, spreading annual naturalized from Europe, in yards 

 and waste places; occasional about Bozeman and other towns of 

 the state. 



122. *SUCKLEYA PETIOLARIS, Gray. 

 A prostrate annual, very much resembling the pigweed-pursely 

 Amaranthus blitoides, Wats.) but with larger and more orbicular 



