CHAPTER VI 



TROPOPHYTES 



WE live in a country subject to changing seasons. Winter 

 follows summer, but in neither case are the conditions 

 extreme. During the summer any interruption caused 

 by drought is only partial and transitory. The fields 

 may become parched and the grass brown, but little else 

 suffers. In other countries where the summer is very 

 dry, the break begins at the onset of the greatest heat. 



Our winters, too, are mild, frosts being intermittent 

 and seldom lasting long. For this reason we are never 

 utterly without flowers. A few hardy stragglers, sur- 

 viving in sheltered places, bloom in November (purple 

 deadnettle, Euphorbia Peplis, Stachys arvensis), while 

 the first pioneers of spring bloom soon after Christmas 

 (Christmas-rose, snowdrop, winter-aconite). The gorse 

 is found in bloom nearly all the year ; it starts flowering 

 after Christmas, and goes on till the middle of summer ; 

 it flowers again in the autumn. Apart from this, however, 

 the frequently low temperature and the prevalence of 

 strong winds, often from the east, make the winter- 

 break, even in England, serious for the greater part of the 

 vegetation. For four to five months there is a marked 

 period of rest, during which most of the vegetation is in 

 a hibernating condition. 



Now, there are two ways by which plants may meet 

 the winter : * 



1. They may possess permanent adaptations providing 

 against the physiological drought of winter. These are 

 evergreen xerophytes, bearing throughout the summer an 

 equipment which is most useful only in winter (see p. 30). 



2. They may discard all or part of their summer char- 

 acters at the close of the vegetative season, assuming a 



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