TYPES AND KINDS OF STEMS 45 



tall cone. The oval form is represented by certain oaks especi- 

 ally when they grow in the open where they are not crowded 

 and the branch system is free to develop. The columnar form 

 is represented by the Lombardy poplar, where there is a central 

 shaft, the leader, and numerous small branches which are nearly 

 erect and nearly parallel with the main axis. Second, the del- 

 iquescent type. This is well expressed in the elm. The branch- 

 ing is somewhat dichotomous* (forking successively into two 

 parts) and diffuse, the main trunk being soon lost. The buds 

 on the young shoots are alternate and two-ranked, that is, 

 regularly in two rows on opposite sides of the stem. The young 

 shoots tend to be somewhat zigzag, with a bud on the outside of 

 each angle. The axillary terminal bud develops in one direction, 

 while the second bud develops a shoot which diverges in the 

 other direction. 



72. Kinds of stems. The great variety of stems may be 

 grouped together under a few kinds. For example, the floral 

 stem 01 floral shoot is that part of the stem whose work it is to 

 bear the flower or flowers. The foliage shoot is the portion of 

 the stem which bears the leaves or foliage, and is often very 

 extensive. Specialized stems, or specialized shoots, are those stems 

 which are unusual either because of their peculiar form or be- 

 cause of the work which they perform, as the cactus, the potato 

 tuber, etc. In fact all stems, properly speaking, are specialized 

 for certain kinds of work. Bud shoots, or buds, form another 

 kind of stem. Within each of these kinds of stems there is a 

 considerable variety. The pupil should study a number of each 

 kind. In the study of the -floral shoot we are concerned chiefly 

 with the flower, and this topic will be taken up in Chapter XVII. 



FOLIAGE SHOOT. 



73. Erect stems. The erect stems are self-supporting. 

 Trees, the vast majority of shrubs, and many herbs belong to this 

 kind. The main axis is erect for a greater or lesser distance, but 



* The branching is only an apparent, not a true dichotomy. 



