56 



ESSENTIALS OF BOTAXY 



the cinquefoil, the white clover, the dandelion, the spurges, 

 the knot-grass, and hundreds of other kinds of plants have 

 found safety in hugging the ground. 



73. Climbing and Twining Sterns.^ — 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 themselves 

 above their neighbors. In trop- 

 ical 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 feet before they can 

 emerge into the sunshine above, 

 and share the light with the trees 

 which support them. In temper- 

 ate climates no such remarkable 

 climbers are found, but many 

 plants raise themselves for con- 

 siderable distances. The princi- 

 pal 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. 13). 



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

 ing branches or leaf-stalks (Figs. 28, 29). 



(3) Twining about any slender upright support (Fig. 30). 



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



Fig. 28. Colling of a Tendril 

 of Bryony. 



