86 PLANT LIFE ON THE FARM. 



plants, not a " seed," nor a root, but a peculiar form 

 of bud called a tuber. 



Tubers. A potato, in fact, is an underground branch, 

 or connected series of buds, forming a swollen subterranean 

 shoot. In this are stored up the starch and other ingredients 

 necessary for the nutrition of the young potato plants. 

 The " eyes " of the potato are really buds, as anyone may 

 see for himself who will examine the " chits " of a sprout- 

 ing potato. These latter bear the same relation to the 

 parent tuber that the shoots which spring from the old 

 " stools" in a coppice or from a pollard willow do to the 

 trunk. The presence of these tubers indicates that, under 

 natural circumstances, the plant requires a long period of 

 rest. To this end food is stored in the tuber, and active 

 growth ceases for a time, till again excited by heat and 

 moisture. It may be inferred from this that continuous 

 growth, were it possible, would be injurious because the 

 climatal conditions are unsuited for it, as, indeed, may be 

 witnessed in the way in which the haulms of the early 

 potatoes are injured by spring frost. 



Fertilisation. In the case of plants grown for their 

 fruit or seed, as in the case of wheat and cereals generally, 

 much attention has naturally to be paid to the conditions 

 which favour sexual multiplication. 



The morphological characters of the plants undergo a 

 change. In general terms, it may be said that the growth of 

 the stem is arrested, and the growth and mode of development 

 of the leaves not only arrested, but more or less profoundly 

 modified, so as to form the parts of the flower. All parts of 

 the flower are constructed on the same original plan as leaves, 



