118 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



though tho calyx, when expanded, probably affords some slight assist- 

 ance, tins is small in comparison with the highly specialised demands of 

 tho staminato and pistillate elements of a flower. 



The first essential, therefore, in flower-bud production is a surplus storage 

 of material, the result of substantial work ; and this must be supported by 

 the second essontial, tho balancing or moderation of the growth. It does not 

 appear that any storage of special substances is made for flower buds ; the 

 matters stored are just as available for and as convertible into growth. 

 Pfeffor says : " In perennial plants a large portion of the assimilated material 

 is convoyed to the permanent organs such as the subterranean roots or 

 rhizomes, and to the stems of trees, while in spring a reverse current 

 always conveys food to the developing buds." 



In consequenco, a continuation or extension of injurious growth will 

 commonly either prevent the formation of flower-buds or effectively weaken 

 them by depriving them of support. 



Artificial restriction of this growth either by branch or root pruning, 

 or by diminishing supplies of soil solutions and moisture, are usually 

 resorted to. Advantageous as such methods are in moderation, extreme 

 treatment in either direction frequently results in further evils. Excessive 

 branch pruning commonly results in greatly multiplied growth, leading to 

 the non-development or deformity of- flower-buds owing to the excess 

 of material available which tho plant cannot dispose of. Excessive root 

 roduction, on the other hand, of ten causes permanent weakening of the tree, 

 and though flowers may be produced they are frequently lacking in some 

 of the essential organs, resulting in non-fertility. 



An interesting example of the effects of excessive root pruning in 

 reference to bud formation and fruit bearing came under my notice a few 

 years ago. Six old espalier Pear trees of one variety at the side of a 

 kitchen garden walk had for some time made a very free growth, but 

 remained unfruitful. Under my direction they were made the subject of 

 an experiment: — (a) two wero root-pruned on both sides, (b) two were root- 

 pruned on one side only, and the remaining two (c) were left un- 

 touched at the roots. The operation was performed in January or 

 February, and nothing special was noticed in the current year ; but in the 

 following year a and B both flowered well ; but while in the latter (those 

 half-root-pruned) the flowers were followed by a fair crop of good fruits, 

 those more severely treated had very few fruits. The last two were in 

 their usual condition, but one was subjected to the same treatment as the 

 others in the following season and gave very similar results. This is 

 only stated as an example of the effects which follow extreme treatment 

 in connection with flower-bud production. Many instances could also be 

 furnished of tho antagonistic influence of excessive branch pruning 

 against flower-bud production and development ; and there is little doubt 

 that undue reduction of growth is quite as much opposed to flower-bud 

 pri duction as excessive growth itself, and much more adverse as 

 regards that pc int alone than non-pruning. But there are other considera- 

 tions rendering the latter undesirable which cannot be entered upon here, 

 as 1 only wished to direct attention to the chief influences controlling 

 hud formation and the difficulties which further experiments might help 

 to elucidate. 



