CHAPTER III 



STEMS 



The vegetative shoot, the ascendinjj axis of a plant, as dis- 

 tinguished from the root or descending axis, consists of stems, 

 leaves, buds, and flowers. These organs are defined by struc- 

 ture and function. Logically, all of these parts of the stem 

 belonging to the vegetative shoot system could be discussed in 

 one chapter, as was the root, but here details must be given and 

 the matter may be presented better by considering the several 

 organs in separate chapters. 



17. The stem defined. — Pomologically, and for most botanical 

 studies, a stem is best defined as any axis of a plant which 

 bears geometrically arranged leaves. Branches are secondary 

 stems. Leaves are lateral outgrowths or appendages of stems 

 and branches. Botanically leaves and stems cannot be sepa- 

 rated by accurate definitions, but in all pomological plants the 

 two organs are readily distinguished. In all of the plants with 

 which this text is concerned leaves differ from stems in their 

 flattened fonn, internal structure, limited growth, and in being 

 geometrically arranged on woody lateral shoots. The places at 

 which the leaves are attached are nodes. The zones between the 

 nodes are iniernodes. 



18. Grape stems. — In the grape, parts of the stem have spe- 

 cial names. Wood of the current season of a vine is called a 

 cane (Fig. 3). Parts of the vine older than one year are old 

 wood. The unbranched main axis, as in other plants, is the 

 trunk. The main divisions of the trunk, or branches, are arms. 

 Newly developed succulent stems are shoots; those which bear 

 leaves only are ivood-shoots, while those which bear leaves and 

 flowers are fruit-shoots. Secondary shoots arising from the 

 main shoots are laterals. The region from which the branches 

 arise is the head. After pruning, short pieces of the bases of 



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