34 AGGREGATION OF BUDS [CH. 



Salisc viminalis, Mulberries, and species of Primus. 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 latei'al 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 al- 

 though these buds appear opposite or whorled, they are 

 only approximately so, the leaves being always spirally 

 inserted, 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, exam- 

 ination 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 



