Photo: J. J. Ward. 



WOOD-SORREL (Oxalis) 



The leaves are seen in "sleep" position. They fold up at night, and seem to with- 

 stand cold better. They also fold in very bright sunlight, and thus avoid overheating. 

 Apart from these conspicuous movements the leaflets continually move slightly in an 

 irregular fashion. They also close if shaken violently. 



Photo: J..J. Ward. 



A CACTUS (MAMMILLARIA) 



The Cactuses are inhabitants of the arid regions of America. 

 The thorns are modified hairs and effectively protect the plant 

 from animals. 



