Stems and Their External Features m 



FIG. 65. Pine trees on Wood River in Oregon. The strong terminal bud 

 continues its development, and the excurrent stem is the result. 



bear the flowers and produce them abundantly only once, we 

 can promote flowering in these roses by trimming away each 

 year all but the long, unbranched shoots. In many other 

 shrubs, as spiraea, barberry, and privet, a few strong lateral 

 buds at the surface of the soil develop each year. This ac- 

 counts for the basal branching of these plants. 



Excurrent and deliquescent stems. When trees have 

 strong terminal buds, the main stem extends to the top and 

 is called excurrent (Latin: excurrens, running out). The 

 spruce has a strong terminal bud, and just beneath it several 

 smaller lateral buds. The terminal bud grows upward, and 

 the lateral buds grow outward, forming a whorl of branches 

 at the base of the season's growth. This is repeated each 

 year, the terminal shoot lengthening the stem, and the lateral 

 buds adding a new whorl of branches. Consequently each 



