690 



CLIMBING PLANTS. 



stem from which the tendril arose is drawn towards the support, and is, as it were, 

 attached to it by a spiral spring. 



Tendrils are always produced in numbers from the stem. Usually one, some- 

 times two tendrils arise from each of the upper nodes, and with the exception of 

 the lowest portion, which is usually quite without them, the stem is very regularly 



Fig. 162. — Stipular tendrils of the common Smilax (Smilax aspera). 



beset with tendrils along its whole length. The advantage of this is that in case 

 one tendril should fail or find no support, a neighbouring one can always take its 

 place. Generally plants with tendril-bearing stems are at a decided advantage in 

 comparison with all other forms of climbing growths, which explains the fact that 

 their number is in considerable excess of the others. In climbing over a shattered 

 rock -face or thick tree -trunk they have a great advantage over plants with 

 twining stems. In some cases the tips of the tendrils fasten on even to the smoothest 

 rocks by peculiar discs, or they grip and hold fast to small projecting portions 



