Forms and Habits of Stems. 43 



Some herbs in the temperate zones lay up a store of food 

 in their stems, leaves, or roots the first season of their 

 growth from the seed. This is consumed the next season 

 in the work of producing fruit. Then the plant dies. Such 

 herbs are biennials. Many plants on the Pacific Coast, like 

 radish and lettuce, store food in the fore part of the season 

 to be used in the latter part. When a plant comes up year 

 after year from some portion that lives underground at 

 least from one growing season to the next, it is called a 

 perennial herb. Some plants which are annual herbs in 

 the Atlantic States live several, or even many years on the 

 Pacific Coast, becoming semi-woody or tree-like perennials. 

 Castor-bean and tomato are notable examples.* Plants 

 with woody stems if small and prone to grow in clumps of 

 many stems from one root system are called shrubs. When 

 a stem or trunk stands apart from others and in time 

 attains a diameter of several inches or a height of twenty 

 feet or more it is called a tree. The same kind of plant 

 may be a shrub in one locality and a tree in another. 

 Shrubs are usually known as bushes. When growing close 

 together over considerable areas they form chaparral or 

 thickets. Trees form groves and forests. Deciduous shrubs 

 and trees shed their leaves at the close of the growing season 

 and remain leafless during the resting season. Evergreens 

 retain the old leaves until new leaves are formed.f 



* Century plants, like annuals and biennials, die as soon as the fruit ripens; 

 but numerous suckers take the place of the old plant. 



f Cone bearers may retain their leaves for several, or, as in the araucarias, for 

 many years. 



