LEAVES 171 



Texture of the Blade. The blade is succulent when it is 

 thick and fleshy, as in live-forever; it is coriaceous when in is 

 thick, fibrous and tough, as in chestnut; it is membranous 

 when it is thin and papery in texture, as the leaves of most 

 herbs. 



Odor. In many leaves glandular hairs or internal secreting 

 tissues form odorous compounds, which are frequently of 

 great economic or medicinal value. The oils of peppermint, 

 spearmint, thyme, eucalyptus, catnip and many others are 

 secreted by the leaves and give an aromatic odor to them. 

 Leaves like stramonium and belladonna have a heavy aro- 

 matic or narcotic odor; most leaves are odorless or have no 

 distinctive odor. 



Taste. All aromatic leaves have characteristic tastes; 

 some are bitter, others astringent, etc. 



Color. To the untrained eye all leaves appear merely 

 green, but, when one observes leaves carefully, there are seen 

 to be innumerable shades of green. The color of the ventral 

 surface is usually darker than that of the dorsal surface and 

 in the poplars the under surface appears nearly white. The 

 leaves of several species of everlasting are silvery white 

 because of the long white hairs which cover the surface. In 

 early spring and fall leaves are usually brilliantly and 

 beautifully colored. Much of the charm of the autumn 

 landscapes is due to the bright colored foliage. 



