44- 



THE MONTANA EXPERIMENT STATION, 



68. IVA XANTHIIFOLIA, Nutt. Careless-weed; Horse-weed; 



Giant Rag- weed. 



A tall, coarse native annual, three to six feet high, with large, 

 heart-shaped toothed leaves opposite on the smooth stem. 

 This is one of the worst weeds in the Gallatin valley, by roadsides, 

 in waste places and cultivated ground, and is not infrequent in 

 low ground east of the Divide, but apparently rare west of it. 



Its small, black seeds seem 

 to be distributed wholly by 

 water and the mud of pas- 

 sage and so it is not apt to be 

 very troublesome except in 

 irrigated districts. [Fig. 11.] 



69. KRINITZKIA CRAS- 

 SISEPALA, Gray. 



Frequent in loose soil with 

 Echinospermutn Redowskii 

 in the Yellowstone region; 

 apparently not west of the 

 Divide. 



70. LACTUCA PULCHEL= 

 LA, DC. Milkweed; 



Wild Lettuce. 



A native perennial of the 

 lettuce family common in 

 all situations throughout 

 the eastern part of the 

 the state; leaves smooth, 

 often with long, slender 

 teeth; flowers blue, closing 

 Fig. 12. Laetuea Scariola, L. a, 1-9; b, nat- m the afternoon. In low 

 ural size; c, enlarged. ground the long under- 



ground rootstocks makes its extirpation difficult. The black seeds 

 with a tuft of hairs at apex are distributed by the wind. 



