28 



HOW PLANTS GROW YEAR AFTER YEAR. 



they must have, in order to bear leaves ; for leaves do not grow on roots. Bat 

 what stem they make is so very short-jointed that it rises hardly any ; so that 



the leaves seem to spring from the top of the root, 

 and all spread out in a cluster close to the ground. 

 As the plant grows, it merely sends out more and 

 more branches of the root into the soil beneath, and 

 adds more leaves to the cluster just above, close to the 

 surface of the warm ground, and well exposed to the 

 light and heat of the sun. Thus consisting of its two 

 working organs only, — root and leaves, ^ the young 

 biennial sets vigorously to work. The moisture and 

 air which the leaves take in from the atmosphere, 

 and all that the roots take from the soil, are digested 

 or changed into vegetable matter by the foliage while 

 exposed to sunshine ; and all that is not wanted by 

 the leaves themselves is generally carried down into 

 the body of the root and stored up there for next 

 year's use. So the biennial root becomes large and 

 heavy, being a storehouse of nourishing matter, which 

 man and animals are glad to use for food. In it, in 

 the form of starch, sugar, mucilage, and in other nourishing and savory products, 

 the plant (expending nothing in flowers or in show) has laid up the avails of its 

 whole summer's work. For what purpose ? This plainly appears when the next 

 season's growth begins. Then, fed by this great stock of nourishment, a stem 

 shoots forth rapidly and strongly, divides into branches, bears flowers abundantly, 

 and ripens seeds, almost wholly at the expense of the nourishment accumulated in 

 the root, which is now light, empty, and dead ; and so is the whole plant by the time 

 the seeds are ripe. 



71. By stopping the flowering, biennials can sometimes be made to live another 

 year, or for many years, or annuals may be made into biennials. So a sort of 

 biennial is made of wheat by sowing it in autumn, or even in the spring and keep- 

 ing it fed down in summer. But here the nourishment is stored up in the leaves 

 rather tlian in the roots. 



72. The Cabbage is a familiar and more striking example of a biennial in which 

 the store of nourishment, instead of being deposited in the root, is kept in the 



