143 



CHAPTEIl XV. 



OF LEAVES, THEIR SITUATIONS, IX- 

 SEliTIOXS, SURFACES, AXD VARIOUS 

 FORMS. 



-TOEIUM, the Leaf, is a very general, but 

 not universal, organ of vegetables, of an ex- 

 panded form, presenting a much greater 

 surface to the atmosphere than all the other 

 parts of the plant together. Its colour is 

 almost universally green, its internal sub- 

 stance pulpy and vascular, sometimes very 

 succulent, and its upper and under surfaces 

 commonly diiler in hue, as well as in kind or 

 degree of roughness. 



Leaves are eminently ornamental to plants 

 from their pleasing colour, and the infinite va- 

 riety as woU as elegance of their forms. 

 Their many ccconomical uses to mankind, 

 and the importance ilwy hold in the scale of 



