MEMOIKS FEOM THE DEPARTMENT OF BOTANY OF COLUMBIA COLLEGE. 41 



middle; stamens five, exserted; style 3.5 mm. long, two-cleft to above the middle, 

 exserted; achene lenticular, 2.5 mm. long, orbicular-oblong or obovoid, conspicuously- 

 biconvex, black, smooth, shining, or somewhat granular and rather dull. 



Quebec to British Columbia, south to New Jersey, Minnesota, Colorado and south- 

 ern California. Also in Europe and Asia. 



