22 USES OF LEAVES. 



nearly to conceal it, they are said to be " imbricated." This last is 

 very prettily shewn in young branches of the common heather ; 

 the others are plentifully exemplified in every field and every garden. 

 The leaflets of compound leaves are also said to be opposite or alter- 

 nate, according to their position upon the petiole. When the plant 

 does not develop a stem, and the leaves spring immediately from the 

 ground, they are called "radical," or "from the root," as well illus- 

 trated in the primrose. 



The space between the stem and the petiole of the leaf, on the 

 upper side of the latter, is called the "axil" or "arm-pit," from its 

 resemblance to that part of the body reversed. It is from the axils 

 that almost all buds, twigs, and flowers are sent forth ; and to denote 

 this, when important to be taken notice of, it is said that they are 

 " axillary." 



In regard to duration, leaves are called " evergreen " when they 

 remain upon the plant or tree during the M'inter in a green and living 

 condition ; and " deciduous " when they fall at the close of autumn. 

 All leaves drop and are renewed sooner or later, the evergreen ones 

 merely enjoying a longer lease, and, like all things of nobler privilege, 

 given as springs of refreshment and beauty M'hen evanescent summer 

 splendours shall have departed. How rich and cheering at mid- 

 winter the bright green of old England's indomitable holly, that 

 sturdy and sacred bush which laughs at frost as complacently as the 

 Christmas it decorates ! 



A few plants are absolutely leafless, as will be mentioned in the 

 proper place ; and there are others, as the furze and cactus, where 

 they are contracted into prickles. 



The use of the leaves is to convert the crude watery matter sucked 

 up by the roots into proper vegetable substance. They have been 

 compared, because of this, to the digestive organs of animals ; and as 

 their functions are respiratory in addition, or of the nature of breath- 

 ing, they have been compared also to the lungs. To enable the 

 breathing and digestion to proceed, the whole surface of the leaf, 

 both on the upper surface and the under, or at least in all land- 

 plants, is clothed with a delicate and transparent skin called the 

 "cuticle." This "cuticle" abounds with little mouth-like openings 

 called " stomatcs," which open and close, according to circumstances, 

 and are very plainly seen with a microscope, if a piece be stripped off 

 and put in a drop of water, with a bit of glass over to keep it flat, and 



