64 



Knud Jessen. 



p. 73), It is not, however, by any means all the flower- 

 buds that are formed which reach maturity. In Copenhagen 

 numerous dead buds were found during 

 autumn and winter. Otherwise such shoots 

 with a dead apical flower-bud behave as do 

 those that flower. The above-mentioned 

 weak shoots which do not at once produce 

 buds, may do so after having lived through 

 Fig. 25. Dnjas ^j^g ^^ perhaps several years of growth in 

 odopetala. Tir.ii i i 



,. ,, . vigour, but I also hnd that such shoots may 



Median section through & ' -^ 



a young flower-bud which ^f^gp ^j^g lapse of a few ycars die in a purely 



would not have attained 



the flowering stage until vegetative Stage, probably suffocated by the 



the following summer . i i • xi 



(Kingigtok in vaigat; тогс vigorous shoots overshadowiug them. 

 Aug 2; ä/,); с, in- ji^QLUND writes that the short shoots im- 



dication of carpels ; st., 



young stamens ; p, petal; mediately put forth ucw short shoots, and 



sp, sepal. 



this is undoubtedly often true. I must 

 regard the short shoots in Dryas octopetala and B. inte- 

 grifolia simply as shoots which have become weakened by 

 competition among themselves, and it is undoubtedly normal 

 for the shoot-develop- 

 ment to end with 

 flower-formation. Ac- 

 cording to the above 

 the branch-system in 

 Dryas^ is sympodial, 

 a few new shoots being 

 produced every year; 

 of these usually one or 

 two are more vigorous 

 than the others. 



The length of the 

 long shoots naturally 



Fig. 26. Dryas octopetala (Iceland). 

 16. 1. 1894. 



a A shoot-apex which shows how the rolling back of 

 the leaves increases towards the apex of the shoot; 

 the uppermost loaves are living the older are dead ; 

 b, a leaf seen from the lower surface; e, a highly re- 

 volute leaf seen from the lower surface (He Igi Jons - 

 son's figures 1. c). 



1 The North American and the North-east Asiatic Dryas Drumondii 

 Richards, behaves in a similar manner. 



