76 EXPERIMENTS TN BLUEBERBY CULTURE. 



hard-Avooded deciduous-leaved trees and shrubs of cold countries this 

 transformation of starch will be found to be caused normally by the 

 changes. i)robably enzymatic, that follow exposure to an alternation 

 of high and low temperatures rather tlian exDosiire to a single low 

 temperature. 



(33) Dormant plants make their early spkinc twic, <;kowth reeore new 



roots begin to develop 



The root growth of blueberry plants in early spring is very slug- 

 gish, in strong contrast to the activity of theii- stems. In the j^lant 

 illustrated in Plate XIII, figure 2, no new root groAvth had taken 

 place up to the time the photograph was made. For their early 

 spring growth blueberry plants seem to depend on the food stored in 

 their twigs the year before. A microscopical examination has shown 

 that the pith and medullary rays of winter twigs are gorged with 

 starch. 



It ma}" be of interest to state here, as bearing on the difficulty of 

 making stem growth exhibited by an improperly wintered blueberry, 

 that the indoor plant shown in iigure 1 of Plates XII and XITI had 

 made considerable new root growth at the stage shown in Plate XII 

 and abundant root groAvth in Plate XIII. The starting of dormant 

 buds appears from this and many other similar cases not to be inthi- 

 enced by the presence or absence of new I'oot growth. 



A practical suggestion based on the late spring root development of 

 the blueberry is that transplanting may ])erhaps be done up to the 

 time of flowering with little injury to the plant. 



(34) T'NLESS pollinated by an outside agency. .SVCII as insects. Tfll. ELOWEKS 



PRODUCE little OR NO FRUIT. 



Many blueberry plants, from seed germinated in September. 11)07. 

 were brought into flower in one of the Department greenhouses dur- 

 ing: the Avinter of 1908-9. When left to themselves the floAvers rareh' 

 ])roduced fruit. The greenhouse contained few pollen-carrying in- 

 sects, a few ants and flies merely, no bees. It was found that the 

 flowers were so constructed as to be unable ordinarily to pollinate 

 themselves. The lack of fruit was evidently due to lack of pollina- 

 tion. "When i^ollinated artificially the floAvers usually produced fruit. 



In its natural position the floAver (fig. 27) is not erect but in- 

 A'erted, the narroAv orifice of the corolla being loAvermost. the nectar 

 Avelling up from the surface of the disk betAveen the base of the style 

 and the base of the filaments. The ten stamens and the style hang 

 downAvard Avithin the corolla, the stpinens being shorter than the 

 style. The pollen Avhen mature drops down fi'om the tAvo anther 

 sacs through the two anther tubes which the stamens of these plants 

 possess and out at the terminal pores. (See fig. 28.) 



193 



