104 



ELEMENTS OF STRUCTURAL BOTANY. 



along the ground, it is trailing or prostrate ; and if, as in 

 the runners of the Strawberry, it takes root on the lower 



side, then it is 

 creeping. Such a 

 shoot as the run- 

 ner of the Straw- 

 berry, which takes 

 root at a distance 

 from the parent 



Pig .. 134 . pl ant > is commonly 



called a stolon. 



150. Many weak stems raise themselves by clinging to 

 any support that may happen to be within their reach. 

 In some instances the stem itself winds 

 round the support, assuming a spiral 

 form, as in the Morning-Glory, the 

 Hop, and the Bean, and is therefore 

 distinguished as twining. In other 

 cases the stem puts forth thread-like 

 leafless branches called tendrils (Fig. 

 134), which grasp the support, as in 

 the Virginia Creeper and the Grape. 

 In the Pea, the end of the extended 

 mid-rib of the leaf is transformed into a 

 tendril (Fig. 135). Sometimes the leaf- 

 stalks themselves serve the same purpose, as in the 

 Clematis or Virgin's Bower. In these cases the stems 

 are said to climb. Our Poison Ivy climbs over logs, &c., 

 by the aid of its aerial roots. 



The stems of wheat and grasses generally are known as 



Fig. 134. Leaf and tendril of Grape-vine. 

 Fig. 135 Tendril of the Pea. 



Fig. 135. 



