Jennings: The Genus Lactuca. 445 



large as the specimen described, but such specimens are not common, 

 the larger plants of rich shaded and moist slopes being in the Pitts- 

 burgh region almost invariably the entirely glabrous and more robust 

 Lactuca canadensis instead of the variety spinulosa. The variety is 

 the common weed of the hay fields in this region, while the species 

 itself is the rarer plant of woodlands and thickets. 



