PROPAGATION 41 



In the absence of light the leaves will not absorb carbonic acid gas, 

 which is essential to the welfare of the plant. The latter must there- 

 fore live on whatevei; reserve material it has stored away in the stems 

 or roots. 



All observant gardeners know the difference between plants grown 

 in light and plants grown in darkness or deep shade. Those under the 

 latter conditions grow rapidly, and plants that are naturally sturdy will 

 assume a weakly, more or less climbing habit, being anxious to reach 

 the sunhght. And every cottager knows that the leaves and shoots of 

 the ' Geranium ' in his window always turn towards the glass and not 

 towards the centre of the room. 



On the other hand plants grown in plenty of light do not develop 

 so rapidly, but each part performs its own function properly and steadily, 

 with the result that the plants are more sturdy, and the stems and 

 shoots become better matured and produce better flowers and fruits. 



Light may therefore be said to have a dwarfing and ripening effect 

 upon plants, while darkness has an elongating and weakening effect. 



Apart from this may be mentioned the fact that the leaves of many 

 plants of the Leguminous order (p. 322), such as the well-known Sen- 

 sitive Plant, go to ' sleep ' — that is, droop — during the night time, and 

 only regain their spreading position in daylight. 



From a cultural point of view, therefore, it is important to notice the 

 effect of light, shade and darkness in plants. Very often a plant which 

 has been grown in strong sunlight will not thrive under the best of 

 treatment ; but when it is shaded or partially shaded, it soon begins to 

 show that it appreciates the altered conditions by the way in which it 

 puts forth new growths. At p. 88 a selection of plants is given which 

 will flourish in shaded or partially shaded situations, while many others 

 are mentioned in various parts of the work. 



PROPAGATION OF PLANTS 



Propagation is the term applied to any method by means of which 

 plants are increased or multiplied in number. Some plants can only be 

 increased in one way, others in several ; but as a rule the gardener 

 usually and not unnaturally selects the method which gives him the 

 quickest and what he considers also to be the best results. In the 

 case of annuals and most biennials (see p. 78) he has no other choice 

 as a rule but to raise them from seeds. This is also Nature's method of 



