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PLANT PHYSIOLOGY AND ECOLOGY 



regions the period of growth is so short that only two aspects 

 appear, the early and the late. Since the period of flowering 

 fluctuates from year to year and since some species bloom for a 

 long time and others for a short one, it is impossible to set accurate 

 limits to each aspect. Each one passes more or less gradually 

 into the next, the first summer flowers appearing before the last 

 spring blossoms have gone. Nevertheless, a careful study of a 

 formation throughout the year will make it clear that the plants 



Fig. 84. Late aspect of the alpine meadow formation, characterized by 

 Campanula petiolata. Rydbergia is seen in fruit. 



that flower in the spring are nearly all different from those of the 

 summer, while the summer aspect contains few flowers that 

 appear also in the next one. As a rule, the prevernal aspect 

 includes the few early flowers that appear about the first of April. 

 The spring aspect comprises April and May; the summer, June, 

 July, and the early part of August; and the autumn aspect the 

 remainder of the year. 



Experiment 59. Study of abundance and of aspects. Select two 

 representative areas in a prairie or meadow formation. Locate a 

 quadrat in each and list the various species, indicating the abundance 



