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NORTON: SPRING FLOWERS IN THE FALL 



not 



In 



the 



has always been more or less of a stumbling block to many 

 students. 



At the present season the varying blooming time of related 

 species always has a direct interest from its evolutionary mean- 

 ing. As an example, take our native and cultivated maples and 

 magnolias. Some species bloom early in the spring before the 



leaves appear, while others wait 

 until the foliage is developed 

 and then bloom well on into 

 summer. From our observa- 

 tions on other groups of plants 

 or on the individuals in one 

 species, this change does 

 seem hard to account for. 

 another case, however, 

 blooming period offers more 

 serious difficulty. The common 

 witch-hazel in this region 

 blooms late in the fall, and yet 

 shows by its behavior that it is 

 a typical spring flowering tree, 

 its fruit developing normally 

 the next season. It seems as 

 though this change must have 

 happened all at once by a big 

 mutation because the winter 

 months would so seriously affect 

 the young flowers and develop- 

 ing fruit that the evolution by 

 slow change would not be able 

 to take place. 



Many other spring flowers have been known to bloom in the 

 fall ; but most of these cases are caused by a moist period follow- 

 ing the summer drought, this alternation of drought and moisture 

 serving the same purpose as that of cold and warmth. It is an 

 interesting thing that this fall or winter blooming is associated 

 with many of our weeds and ornamental plants introduced from 



Fig. 1. Flower buds of Cornus 

 Mas, March, 1912, showing fruits of 

 the previous fall. In the lower 

 branch the bud scales have been re- 

 moved. (X H) 



