2g: 



Canadian Record of Science. 



Fig. 7. Spiraea trilobata vanhouttei. a. Leaves from a normal vege- 

 tative shoot of the season, b. Leaves from a flowering branch ; 1-3 developed 

 during the period of inflorescence ; 4-7 developed on lateral shoots of the 

 flowering axis after the inflorescence had passed, x \ 



of about 94 sq. cm. This latter may be taken as the typical 

 size of the leaf for this region. But the same tree commonly 

 produces leaves of yet larger size on the more vigorous shoots, 

 especially the short branches arising from the main trunk 

 where they get an excess of nutrition. Such leaves not un- 

 commonly attain a breadth of 20 cm., and an area of 276 sq. 

 cm. It is obvious then, that under ordinary conditions of 

 growth in a good soil, the foliage varies somewhat widely, 

 though the general type conforms to that of the second 

 example. 



In the woodlands of this district, the linden forms a 

 somewhat abundant undergrowth through the development of 

 suckers of very vigorous growth. In all such cases, the foliage 

 is unusually large, being of the general type of the third 

 example, and therefore conforming to the largest leaves found 

 upon nature trees. When such young growths are much 

 pruned, or when they arise from old stumps, the plant acquires 

 a relatively very extensive root system which supplies it with an 

 unusual amount of food materials. Under such circumstances 



