Longevity of Herbaceous and Woody Stems 147 



This distinction may be expressed in another way by saying that 

 shrubs branch underground, while trees branch only above 

 ground. Most shrubs are less 

 than 10 feet in height, but some, 

 like the staghorn sumac, may reach 

 a height of 20 feet, or, like the 

 bamboo, 40 feet. Most trees are 

 between 25 and 200 feet in height. 

 However, the distinction be- 

 tween herbs, shrubs, and trees is 

 not one of size. Herbaceous plants, 

 like the sunflower, may reach a 

 height of 20 feet, and in the tropics 

 corn and bananas a height of 30 

 feet, while some shrubs are only a 

 few inches in height and some of 

 the dwarf trees of Japan that are ^ . . a ^ ■ c 



-' ^ riG. 85. Japanese dwarf pine, borne 



a century old are less than 5 feet of these small potted trees are a cen- 



in height. ^""'y ''^'^■ 



Some of the oldest trees known were seedlings 3000 years ago. 

 Many trees now standing are over a thousand years old. The 

 average age of the older trees in our Eastern forests, however, 

 is much less than this, ranging from one to three hundred 

 years; in some of the Western forests, three to five hundred 

 years. 



Plant characteristics and the plant-producing arts. The dif- 

 ferences in the habits of growth, longevity, and materials stored 

 by plants has led to specialization among those who grow plants. 

 For many evident reasons the most important art of growing 

 plants is agriculture. The farmer deals entirely with herbs and 

 largely with annuals, though biennials and perennials may be 

 grown for forage crops. He is for the most part concerned with 

 plants that accumulate foods in a highly concentrated form in 

 seeds. He transforms some of this food into meat and dairy 



