222 



BULLETIN 68. 



7. Populus laurifolia (or P. 

 Certinensis). Slow-grow- 

 ing shoot. ( 2 /T, nat. size. ) 



where wind- 

 breaks are de- 

 sired quickly. 

 Like the Car- 

 olina poplar, 

 it has a strong 

 upright habit 

 of growth." 



5. Popu- 

 lus laurifo- 

 lia (lyedebour 

 Icones Planta- 

 rum Nov. 

 Ross. v. 23, t. 

 479 (1834). 

 P. balsami- 

 f era, \&r. laur- 

 ifolia, Wes- 

 mael, D. C. 

 Prodr. xvi. part ii. 

 330. P. Certinensis, P. 

 Petrovski and P. Bereolensis 

 of American horticulturists). 

 CERTINENSIS POPLAR, Figs. 7, 8 ; j. 

 fig. i. This Siberian species is the most 

 important of the recently introduced 

 poplars. It is a very rapid-growing and 

 hardy tree, with a strong central leader, 

 and a very heavy dense foliage. It is 

 the Old World representative of our 

 cotton wood. The foliage upon the old 

 wood or upon slow-growing shoots (Fig. 

 7) is very unlike that upon the vigorous 

 branches, and it is almost identical with 

 that of the balsam poplar, being broadly 

 oval, with finely serrate margins, and 

 whitish beneath. The twigs, also, are 

 cylindrical. But the strong shoots are 



