40 THE MONTANA EXPERIMENT STATION. 



51. ERIGERON CANADENSIS, L. 



Ragweed; Fireweed; Horseweed. 



A slender, hairy annual with narrow leaves and a large ter- 

 minal broom of greenish flowers and cottony fruit imported from 

 the eastern United States. Becoming frequent in waste places, 

 gardens and grain fields, and a serious pest in the Flathead valley. 

 Size varies from a few inches to several feet; seed spread by 

 the wind! 



52. EUPHORBIA GLYPTOSfERMA, Engelm. Carpet Weed. 



A small, much branching annual, lying flat on the ground and 

 forming circular carpets a foot or more in diameter. Apparently 

 native but frequent by roadsides and in grain fields and waste 

 places; rarely troublesome. 



53. EUPHORBIA MARGINATA, Pursh. Snow on the Mountain. 



An annual, one to two feet high, with milky juice and upper 

 leaves white margined. In waste places and along railway 

 grades from Miles City to Glendive. Coming in from the east- 

 ward. Reputed poisonous. 



54. FRANSERIA HOOKERIANA, Nutt. 



An annual weed very much like the Ragweed (Ambrosia arti- 

 misiaefolia), but with fruit of conspicuous burs. Frequent in sandy 

 soil along highway's and in streets and waste places in many 

 parts of the state east of the Diyide. Possibly native, although it 

 has all the habits of an introduced weed. 



55. GAURA COCCINEA, Nutt. Butterfly Weed. 



A native perennial with long, deeply penetrating rootstock, 

 frequent in new ground and occasionally found in grain fields and 

 fallow land, mainly as the variety glabra, T. & G. Leaves nar- 

 row, flowers white or rose-colored, turning to scarlet in fading. 



56. GAURA PARVIFLORA, Dougl. 

 A tall, hairy annual or biennial, two or three feet high, with 

 small flowers and long, slender spikes of spindle-shaped fruit, oc- 

 casionally troublesome in grain fields and waste places in the Mis- 

 souri river region. Apparently introduced from eastward. 



