22 PLANT LIFE ON THE FARM. 



career light is not essential may be of the greatest conse- 

 quence to cultivators ; and it is probable that the future 

 will show us much more fully how great is our indebted- 

 ness to them. For our present purpose, we have to deal with 

 plants producing leaves, to point out some of the work 

 which the leaves do, and to give some indication of how 

 they do it. 



Unlike the root, which originates from within the sub- 

 stance of the plant and breaks its way out to the surface, 

 the leaf, as has been stated, is a direct production from the 

 surface of the stem or branch. It is one of the charac- 

 teristics of a root not to produce leaves ; it is one of the 

 attributes of the stem and its subdivisions to clothe them- 

 selves with these appendages. 



In form, texture, size, the leaf presents infinite variety. 

 Sometimes it is a mere dry scale, sometimes a thick fleshy 

 excrescence ; now it offers a broad banner-like surface, now 

 it is reduced to the form and dimensions of a needle. 

 Sometimes it is all in one piece, the " blade " being un- 

 broken at the edge, or variously notched and indented ; at 

 other times the blade is made up of few or of an infinite 

 number of separate segments or leaflets. If the blade is in 

 one piece, it is " simple," as the leaf of wheat ; if in many 

 pieces, as the leaf of clover, sainfoin, or tares, it is " com- 

 pound." Yery often it has a stalk or " petiole," sometimes 

 it has none. Sometimes it has appendages at its base called 

 " stipules," well seen in vetches or clover; while the leaves 

 of all grasses, including all the cereals, are provided with a 

 little membranous tongue or outgrowth from the junction 

 of the sheathing stalk of the leaf with the blade, which is 

 called a " ligule," and which, though often overlooked, is of 

 some moment to the grazing farmer, as affording one means 



