STRUCTURE AND LIFE HISTORIES 
observation discloses the fact that these are really pseudo- 
whorls, since the branches do not emerge at precisely the 
same level on the trunk, as in true whorls. Both because 
they are older, and because they receive less light, the 
FIG. 305. Elm tree (Ulmus americana), showing deliquescent trunk. 
lower branches are longer, and the gradual decrease in 
length from below upward, combined with the excurrent 
habit of the trunk, gives the tree a pyramidal outline when 
it grows free in the open. This shape is modified by 
