STEMS. 



45 



the white clover, the dandelion, the spurges, the knot-grass, 

 and hundreds of other kinds of plants have found safety in 

 hugging the ground. 



68. Climbing and Twining Stems} — Since it is essential 

 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 them- 

 • selves above their neighbors. In tropical forests, where the 

 darkness 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 



yiG. 29. The Dandelion ; a so-called Stemless Plant. 



feet before they c'an emerge into the sunshine above, as those 

 shown in the frontispiece have probably done. In temperate 

 climates no such remarkable climbers are found, but many 

 plants raise themselves for considerable distances. The prin- 

 cipal 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, Tig. 14. 



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



