TREES 561 



Winter buds are best studied on trees. The subject of 

 buds, their protection and their development, was discussed 

 on page 311. 



It should be remembered that the foliage of trees has the 

 usual function of leaves, namely, to carry on transpiration 

 and to make starch. (See page 313.) Place branches of 

 different kinds of trees, such as cherry, maple, elm, and 

 others, in vessels containing equal quantities of water. The 

 twigs should have very nearly the same leaf area. It will 

 be noticed that different quantities of water are absorbed, 

 and also that some of the twigs will be wilted sooner than 

 others. This illustrates in a very rough way the rate of 

 transpiration for the different species. The quantity of water 

 given off from a tree is enormous. Mr. Ward in his study 

 of the oak estimates that an oak may have 700,000 leaves, 

 and give off during the summer no less than twelve tons of 

 water from its foliage. This makes apparent the need of a 

 large root system and also of plenty of rainfall. 



The leaf arrangement is interesting. There is a prevailing 

 symmetry and orderliness in the position of leaves. Study 

 their arrangement on an elm tAvig and a maple, and 

 compare. 



The leaf mosaic, or arrangement, so as to cover all open 

 space and yet not shade other leaves, should be studied in 

 different trees. The effect of one-sided illumination should 

 be noted in trees growing at the edge of a forest, or where 

 shaded elsewhere. 



For purposes of identification and for its beauty, study 

 the venation, and also the leaf form in different species. A 

 study of the terms: netted-veined, serrate, crenate, palmate, 

 etc., for definition merely, is not nature-study. If these things 



