56 



The present paper will only be a report — brief as that of a sentry 

 should be — about "some silent invaders of our fields." 



Lactuca scariola L., the Prickly Lettuce, is becoming abundant around 

 Mount Royal. It seems useful to draw attention to this rather cumbrous 

 weed. We do not notice it, though, on the South Shore, nor on the Lower 

 St. Lawrence. 



Lactuca Scariola (Prickly Lettuce) 



Iva xanthifolia Niitt., is a sturdy Ambrosiaceae brought into Montreal, 

 we believe, with the American coal. We have not seen it since our report 

 in the "Naturaliste Canadien" (XL. 87, 1913). But it is to be watched, 

 since Mr. M. L. Fernald finds it quite at home somewhere in Maine, near 

 our borders. (Rhodora XIL 139). 



Senecio vulgaris L., the Common Groundsel, we find rather sparingly 

 around Montreal, but extremely abundant in Temiscouata County, owing 

 to the proximity of the Maritime Provinces where it is a pernicious plant. 

 On the Lower St. Lawrence, the conditions seem adapted to the establish- 

 ment of Senecio since the native flora offers also: S. aureus L., 5. Balsamitae 

 Muhl., S. discoideus (Hook.) Britton, and the giant halophytic S. pseudo- 

 Arnica Less. We have reasons to think that Senecio vulgaris L., is travelling 

 northwestward. 



Vaccaria Vaccaria L., Britton, one of the worst weeds of the grain 

 fields of the West, was collected once in Longueuil, in 1912, by one of our 

 pupils, Mr. C. Lajoie. 



