34 AGGREGATION OF BUDS [CH. 



Salix viminalis, Mulberries, and species of Prunus. In 

 other cases the accessory buds are superposed, and it 

 depends on the species whether the upper or lower bud 

 of each group is the dominant one. 



Another feature in the arrangement of buds, and with 

 consequent effects on the branching which results, is the 

 tendency to be grouped on particular regions of the twigs. 

 In the Oak, for instance, most of the buds are clustered 

 at the tips of the twigs, and in certain Cherries and their 

 allies e.g. Prunus Padus the characteristic clusters of 

 buds on the short lateral dwarf-shoots, or spurs, are very 

 noticeable. 



In the Pines (Fig. 9) and Firs (Fig. 13), again, very 

 few of the leaf-axils carry buds capable of forming long 

 shoots at all, but a cluster of axillary buds occurs at the 

 tip of each branch, and when these grow out they appear 

 as if all sprang from the same level, in whorls, whereas 

 each bud is really at a slightly different level from its 

 nearest neighbour. Similarly on the horizontal twigs of 

 the Spruce, Douglas Fir and Silver Fir only a few buds 

 are formed in one or two of the leaf-axils, though there 

 may be hundreds of leaves on the twigs, and although 

 these buds appear opposite or whorled, they are only 

 approximately so, the leaves being always spirally in- 

 serted, as close observation shows. All these matters 

 may have their effects in the branching which results 

 from the elongation of the buds the following spring, 

 and therefore on the form of the branch-system or crown 

 of the shrub or tree concerned. 



Yet another peculiarity of buds, as regards their 

 position, deserves closer attention. In some cases, exami- 

 nation of the leaf-axils in summer or autumn, while the 

 leaves are still on the tree, fails to disclose any buds 

 at all. Nevertheless they are present, but are buried 



