I00 SIZE OF LEA VES. [CHAP. 



relation to the thickness of the stem. This is clearly 

 shown in the following table : 



Impression of Stalk below the Sixth Leaf. 



beam. Beech. Elm. Nut Sycamore. Lime. Chestnut. 



Elder. Ash. Walnut Ailanthus. Chestnut. 



Diameter Approximate 



of Area 



Stem of Six Upper Leaves 

 in inches. in inches. 



Hornbeam ...... '06 14 



Beech ....... '09 18 



Elm ......... " 34 



Nut ....... : . -13 55 



Sycamore ..... '13 60 



Lime ........ 'H 60 



Chestnut ....... '15 72 



Mountain Ash .... '16 ... 60 



Elder ........ '18 ... 93 



Ash ......... 'i8 ... too 



Walnut ....... -25 220 



. Ailanthus ...... '3 ... 240 



Horse Chestnut .... '3 ... 300 



In the Elm the numbers are TI and 34, in the 

 Chestnut '15 and 72, and 'in the Horse Chestnut the 

 stem has a thickness of '3, and the six leaves have 

 an area often of 300 square inches. Of course, how- 

 ever, these numbers are only approximate. Many 

 things have to be taken into consideration. Strength, 

 for instance, is an important element. Thus the 

 Ailanthus, with a stem equal in thickness to that of 



