24 Plants and their Ways in South Africa 



Notice Oxalis plants at night. Leaves and flowers are all 



closed. In the morning they open. On very bright days the 



leaves go to sleep, while the flowers remain open. On cold 



days they remain closed, so heat as well as 



light has something to do with the closing 



of leaves. 



Plants grown in sunlight have a sturdy 

 appearance, and the leaves are well de- 

 veloped. Well-developed leaves would be 

 of little use to a plant grown in darkness. 

 It is best for the stem to push out as 

 rapidly as possible in search of light. If 

 a plant remains in darkness, the leaves 

 remain small and undeveloped, while the 

 internodes lengthen as fast as possible. 

 The plant in Fig. 30 grew under the shelter 

 of a large rock. The part in the pot grew 

 on the sunny northern side, while the piece 

 at the left grew in a more shaded place on 

 the southern side. Fig. 31 is the picture 

 of a very compact little plant when it is growing at home in 

 the karroo near Beaufort West ; but while boxed up for the 

 post it started on a journey of its own in search of light. 



While leaves grow more rapidly in light, the stem grows 

 less rapidly. 



Fig. 31. — The boxed-np 

 Karroo plant sent forth 

 a shoot in search of 

 light. Observe the 

 diflference in position 

 and size of leaves. 



