THE ANGIOSPERMAE : STEMS 843 



until the node is some distance from the apical meristem zone, so that the 

 bud meristem seems to be secondary, that is to say, it has no direct con- 

 nection with the apical meristem. The reverse, namely, the earlier develop- 

 ment of the bud rudiment, occurs chiefly in flowering shoots, where the 

 leaf subtending the flower may have a very limited power of growth, or 

 mav be entirelv abortive, so that the flowers (as in many Cruci ferae) appear 

 to have no subtending leaf at all. 



The precocious development of axillary buds may also occur in vegetative 

 shoots, a well-known example being Berberis, in which the leaves of the 

 long shoots are transformed into spines, and in their axils stand rosettes of 

 true leaves, the precociously developed leaves of the axillary shoots, which 

 are not due to elongate into branches until the following season. 



The suppression of bud growth, on the other hand, is usually associated 

 with late appearance. It often happens in the axillary buds themselves that 

 the enveloping scales, which are modified leaves, develop no axillary buds of 

 their own until the bud begins to grow, which may be a year after its forma- 

 tion. These buds are very small and have little power of growth. When 

 the axillary branch has grown, some of these buds are left at its base, where 

 they remain dormant so long as the branch continues its growth. Eventually 

 thev are submerged by the expansion of the main stem, and they may remain, 

 embedded but alive, long after the axillary branch which bore them has 

 disappeared. Every old tree carries hundreds of such hidden buds. Should 

 anv catastrophe befall the active portion of the tree, the diversion of food 

 materials to these buds starts them growing and they emerge as the vigorous 

 " stool shoots " which may spring out like a thicket from the stump of a 

 tree which has been felled or from the trunk of a tree which has been lopped 

 of its branches. 



Considerable difi^erences may be observed between the vigour of growth 

 of difi^erent branches, which are usually due to diflferences in the amount of 

 food available, whether by the accident of favourable position or the availa- 

 bility of stored reserves. In the short shoots, with their closely set leaves, 

 the movement of foodstuff's elaborated by the leaves seems to be less free 

 than in the long shoots, with the result that they become loaded with carbo- 

 hydrate reserves. This seems to encourage flower formation, and in many 

 plants, especially fruit trees, it is noticeable that flowering is usually confined 

 to the dwarf branches or " spurs." The aim of a cultivator is to encourage 

 the production of spurs over the greatest possible length of stem, and this 

 he does by judicious pruning. In the summer he removes the upper third 

 of each young shoot. This diverts nutriment to the lower buds. Of these a 

 few of the uppermost will start to grow into leafy shoots, but those at the 

 base will receive only enough to encourage them to dwarf growth. When 

 winter comes he cuts the shoot back nearly to the uppermost of these spur 

 growths, leaving a top bud to continue next year the growth of the branch, 

 while the spurs flower and bear fruit. Thus the whole branch system 

 can be kept " furnished," as it is called, with spurs, whereas in trees 

 that have been left alone there will be lengths of stem in which the 



