STEMS 



73 



out their leaves and flowers from a very short stem, which 

 hardly rises above the surface of the ground. 



88. Climbing and Twining Sterns.^ — Since it is essen- 

 tial to the health and rapid growth of most plants that 

 they should have free access 

 to the sun and air, it is not 

 strange that many should 

 resort to special devices for 

 lifting themselves above 

 their neighbors. In tropi- 

 cal forests, where the dark- 

 ness of the shade anywhere 

 beneath the tree-tops is so 

 great that few flowering 

 plants can thrive in it, the 

 climbing plants or lianas 

 often run like great cables 

 for hundreds of feet before 

 they can emerge into the sun- 

 shine above. In temperate 

 climates no such remarkable 

 climbers are found, but many 

 pla,nts raise themselves for 

 considerable distances. The 

 principal means to which they resort for this purpose are : 



(1) Producing roots at many points along the stem 

 above ground and climbing on suitable objects by means 

 of these, as in the English ivy (Fig. 16). 



(2) Laying hold of objects by means of tendrils or 

 twining branches or leaf-stalks, as shown in Figs. 40, 41. 



1 See Kerner and Oliver's Natural History of Plants, Vol. I, p. 669. 



Tia. 39. — Lianas strangling a Palm. 



