THE LAUREL FAMILY 



129 



1. When we rub its Leaves, a fine aroma is produced, caused 

 by a volatile oil contained in them. The same oil occurs also 

 in other pj^rts of the tree and 

 chiefly in the inner part of its 

 bark. 



The young shoots of the tree 

 are often of a dark crimson 

 (Plate No. 632, 2), especially in 

 trees growing on high moun- 

 tains. In the description of the 

 Mango tree (page 26) we have 

 already learnt that this is an 

 indication of active breathing 

 in the young parts of a plant. 

 We can artificially produce the 

 reddening of leaves l)y wound- 

 ing them, for l)y doing so we 

 increase the action of breath- 

 ing, by which the plant seeks 

 to heal the wound. (Compare 

 the increase of breathing by 

 which fever is accompanied.) 

 The vigorous process of breath- 

 ing increases the heat produced by the oxidation of carbon, which 



naturally benefits a plant growing in the 

 cool climate of higher elevations. At the 

 same time the red tint in the cells of young 

 leaves may protect the chlorophyll-granules 

 from the destroying eftect of too intense 

 light. 



Another characteristic of the opposite 

 and leathery leaves of the Cinnamon tree 

 are the three conspicuous parallel ribs 

 running from the base to the tip (fig. 119). 

 2. The greenish Flowers are seated on 

 axillary, sometimes terminal panicles. The 

 perianth is composed of two united whorls 



9 



Fig. 1 19. — Flowering branch of the 



Cinnamon tree (Cinnamomum 



zeylanicum). 



y'"-'. 



V i 



Fig. 120. — Flower of 



Cinnamon 



(longitudinal section, 



much enlarged). 



