STEMS 



127 



What natural habits of growth make it impossible for the 

 horse-chestnut, ailanthus, and catalpa to produce excurrent 

 trunks? Such trees are said to have deliquescent trunks. 

 Name forest trees which have trunks of this type. 



Field Work on Trees 



Make excursions into forests, fields, and parks. Study 

 trees growing in the open and compare them with trees of 

 the same sort which are found growing in groves. Make 



FIG. 51. White pine. 

 (Photographed by W. C. Harbour.) 



FIG. 52. Hickory. 

 (Photographed by W. C. Barbour.) 



notes of differences in height, shape, position of branches, 

 etc. 



Make lists of excurrent trees, deliquescent trees, and also 

 those which seem to be of an intermediate form. Find a 

 tree which is normally excurrent, as the pine, spruce, syca- 

 more, but which shows a forked trunk. Try to determine 

 the cause of the difference. 



