176 GENERAL BOTANY 



the day, they catch the sun's rays and let very little of 

 the light and heat pass between to the ground below, 

 at night the heat from the earth and the hot air can 

 easily rise up and pass away. It is for this reason 

 that the plant makes such an excellent roadside tree. 



Reduction in leaves and leaflets 



CASUARINA EQUISETIFOLIA, Forst. 



01 Examine the smaller branches of CASUARINA, a 

 tree, which, though not a native of India, grows very 

 well here, and is planted very commonly in waste 

 sandy places near the sea, for the sake of fire-wood, 

 and also in peoples' gardens in the plains or the hills. 



The branches are brown and rough with sharp 

 scales which occur in whorls or circles. On these 

 branches arise slender cylindrical green organs, which, 

 being green, do the work of leaves. But these green 

 organs are not leaves. If you examine one, you 

 will see that it is marked at intervals of about one- 

 sixth inch with a whorl of very small triangular 

 scales. There are shallow grooves too running longi- 

 tudinally down from one whorl of scales to the next, 

 and alternating with the next set of grooves. 



Now, no leaf structure bears whorls of scales, or 

 anything else but hairs or glands. 



These green organs are in fact branches, and the 

 small triangular scales which they bear represent 

 leaves, though very much reduced and as leaves quite 

 useless. As we find in nearly all cases of opposite 

 or whorled leaves, those of one node stand not just 

 above, but in lines between those of the next, so here, 



