CHAPTERS IN PLANT LIFE 



II— THE PLANT AND THE SEASONS 



By S. LEONARD BASTIN 

 Illustrated with Photographs by the Author 



THE changes which come over the 

 world of plants with the passage 

 of the seasons are the most dis- 

 tinctive features of the countryside. At 

 the approach of winter the greater number 

 of trees and shrubs, in common with most 

 perennial species, pass into a state of 

 quiescence from which they will not emerge 

 until the arrival of the spring. Such 

 a course is only possible in conditions 

 which involve a cessation of vegetable 

 activity that is practically universal. In 

 the tropical forests the trees are almost 

 without exception evergreen in habit, 

 and it is necessary that they should be so, 

 if they are to hold their own in the fierce 

 struggle for existence. The welfare of 

 the tree depends upon the extent to which 

 it can keep the soil beneath it in a state of 

 dense shade. Underneath the spreading 

 branches the ground is littered with ger- 

 minating seeds, only waiting for a few 

 raj-s of sunshine to enable them to start 

 into a vigorous upgrowth. Should the 

 tree become denuded of its foHage for even 

 a short while, it would soon find itself 

 surrounded by a host of foiinidable rivals 

 that might threaten its very existence. 

 No such considerations arise in the case 

 of trees growing in temperate climes for at 

 any rate half of the year. In the bitter 

 days of winter there is no fear that the 

 myriads of seeds which lie buried in the 

 soil will start into hfe. Even should 

 they do so during the first few weeks of 

 warm weather they will scarce have grown 

 into small plants before the branches 

 above them are tliick with rustling 

 leaves. 



To the lover of Nature every spring- 

 time comes with freshness, offering as it 

 does a new opportunity to observe one of 

 the most amazing sights in the whole 



world. The bare trees, the leafless hedges, 

 and the brown earth are in a few short 

 weeks transfoiTned as by the touch of a 

 magician's hand. So great is the up-rush 

 of life that it is quite impossible to separate 

 oneself from the joyousness of the resur- 

 rection. It is interesting to dwell upon 

 the underlying causes which bring about 

 this annual change. The question is one 

 which must often arise — how do plants 

 know the seasons ? At first sight it may 

 seem that a renewal of activity is simply 

 due to the fact that the cold weather is 

 gone ; but this does not offer a complete 

 solution of the problem. 



Late last autumn the conditions were 

 for weeks as uniformly mild as they are at 

 present, yet the trees did not start into 

 leaf. It may be suggested that it is the 

 increase in the intensity and the amount 

 of sunshine which arouses the plants 

 from their winter slumber. This can 

 hardly be the case with the large number 

 of herbaceous plants with rootstocks 

 inches below the surface of the soil, yet 

 these respond to the call of spring no less 

 readily than the deciduous trees and 

 shrubs. Even more difficult to explain 

 is the behaviour of the aquatic species, 

 such as the Water Lihes. The roots of 

 these plants are buried in mud many feet 

 deep under water — how can they possibly 

 be aware of the arrival of the new season ? 

 Yet quite early in the spring these plants 

 begin to stir into activity. Most strange 

 of all in connection with the problem of 

 the plant and the seasons is the story 

 of the Soldanellas, small plants which 

 exist on the lower slopes of the Alps. 

 When the flower stems are in their most 

 acti\-e state of growth they release a 

 considerable amount of heat. In this 

 way they \\'ill bore a course up through 



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