STEMS AND BRANCHES AND THEIR USES 197 



the soil is too soft or too poor to support tall plants, we find 

 many plants with trailing stems. The cranberry is a trailing 

 bog plant. Some trailing plants also live in open woods; 

 they are likely to form their flowers or their flowers and leaves 

 very early in the spring, so that they ripen their fruits and 

 even perhaps manufacture much of the year's supply of food 

 before the leaves of the trees grow large enough to reduce 

 their light. The trailing arbutus of the northern woods, 

 whose flowers often open under the snow, is a trailing plant 

 that has become adapted to life in forests. 



Many trailing plants, as well as many erect plants, bear 

 alternate leaves ; but the stem of a trailing plant is likely 

 to be twisted, so that, although the leaves borne at successive 

 nodes really arise from different sides of the stem, the side 

 from which any leaf arises is turned upward at that particular 

 node. So, because of the twisting of the stem, all the leaves 

 are in the most favorable position with reference to light. 

 Usually the roots of a trailing plant grow in clusters at the 

 nodes, and if by accident the stem is broken or killed between 

 two nodes, the part on either side of the injured place becomes 

 a separate plant. The power of multiplying in this way is 

 important to a trailing plant, which because of its position is 

 especially liable to injury. The branches of a trailing plant 

 may also be separated and live as independent plants. 



217. Climbing Stems. Climbing plants, like trailing 

 plants, can grow to a considerable length and can produce 

 many leaves, flowers, and fruits without using a large amount 

 of substance to build up a thick stem. The special advan- 

 tage of climbing plants over trailing plants is that they can 

 grow in the same localities that erect plants grow in, and 

 so can compete with erect plants for access to sunlight 

 a thing which trailing plants in general cannot do. Some 

 climbing plants, such as beans and peas, are soft-stemmed 

 annuals ; others are woody-stemmed perennials, like the grape 

 and the Virginia creeper. It is in tropical forests that woody 



