136 PHARMACEUTICAL BOTANY 



3. A mixed bud is a young shoot bearing concealed unexpanded 

 leaves and flowers. 



Classification of Buds According to Position on the Stem. i. A 

 terminal bud is one which is located on the end of a stem (shoot). 

 It is capable of elongating into a shoot which bears leaves or both 

 leaves and flowers. 



2. An axillary or lateral -bud is one which arises in the leaf axil. 

 It is capable of giving rise to a side branch or to a flower. Occa- 

 sionally axillary buds do not develop and are then called dormant 

 buds. 



3. An adventitious bud is one which occurs on some position of the 

 stem other than at its apex or in the axil of a leaf. Such buds may 

 be seen developing along the veins of a Begonia leaf or along the 

 margin of a Bryophyllum leaf after these have been planted in 

 moist soil for several days. 



4. An accessory bud is an extra bud which forms in or near the 

 leaf axil. 



Classification of Buds According to Their Arrangement on the Stem. 



1. When a single bud is found at each joint or node of a stem, the 

 buds are said to be alternate. 



2. When two buds are found at a node they are opposite. 



3. When several buds occur at a node they are whorled. 



THE STEM 



The stem is that part of the plant axis which bears leaves or modi- 

 fications of leaves and its branches are usually arranged with mathe- 

 matical regularity. 



Stems usually grow toward the light and so are heliotropic. 



The functions of a stem are to bear leaves or branches, connect 

 roots with leaves, and conduct sap. 



When the stem rises above ground and is apparent, the plant is 

 said to be caulescent. 



When no stem is visible, but only flower or leaf stalks, the plant is 

 said to be acaulescent. 



Stems vary in size from scarcely ^ 5 inch in length, as in certain 

 mosses, to a remarkable height of 400 feet or more. The giant 

 Sequoia of California attains the height of 420 feet. Some of the 



