THE STEM 



83 



92. Biennials, as the name implies, live for two years. 

 Their energy during the first season is spent chiefly in laying 

 by a store of nourishment, 

 usually in the tissues of 

 fleshy roots (70). By this 

 means they get a good start 

 in the second season and 

 mature their seeds early. 

 Many of our common gar- 

 den vegetables, such as tur- 

 nips, carrots, parsnips, and 

 cabbage, belong to this 

 class. Where is the nour- 

 ishment stored in the cab- 

 bage? 



93. Perennials are plants 

 that live on indefinitely, like 

 most of our forest trees 

 and woody-stemmed shrubs. 

 Woody stems are usually perennial and may live for hun- 

 dreds and even thousands of years, as those of the giant 

 sequoias of California, and the famous chestnut of Mt. 

 Etna. 



94. Herbaceous stems are more or less succulent and die 

 down after fruiting. They are usually annuals, though some 

 kinds, like the garden geraniums and the common St.-John's- 

 wort, show a tendency to become woody, especially at the 

 base, and live on from year to year. Others, such as the 

 hawkweed and dahlia, die down above ground in winter, 

 but are enabled to keep their underground parts alive indefi- 

 nitely, through the nourishment stored in them, and are 

 thus perennial below ground and annual above. Woody- 

 stemmed annuals, such as the cotton and castor oil plant, 

 are not, properly speaking, herbs. In the tropical countries 

 to which they belong they are perennial shrubs, or even 

 small trees, but on being transplanted to colder regions 



Fig. 93. — A liicimial plant, mullein, in 

 winter conditii^n with stem reduced to 

 little more than a disk supporting a rosette 

 of leaves. Notice how close they cling to 

 the earth, and compare them with their 

 fruiting condition a few months later aa 

 shown in Fig. 237. 



