io PRESENT-DAY GARDENING 



the conduction of sap until finally the supporting tree 

 is killed outright. It may be that in the struggle for exist- 

 ence this character has been developed in plants with thin 

 stems to enable them to fight successfully for " a place 

 in the sun." Without it they would stand a poor chance 

 against umbrageous forest trees. " Sometimes one finds 

 the hard basal parts of a liane (climber) twisted and coiled 

 apparently round nothing. This is due to the fact that the 

 original support has been killed, and then slowly rotting, 

 has been denuded away by the wind and rain. Thus, many 

 a liane of the tropical forest seems to have made use, 

 when young, of some living plant with fairly thick erect 

 stem as its first support, up which it has climbed into the 

 crowns of higher trees" (Kerner). Sometimes the 

 climber gets the worst of it, the encircled tree expanding 

 until the pull on the coils is so great that the climber is 

 killed. 



Darwin in his Movements of Plants shows how all the 

 growing parts of plants are continually circumnutating, and 

 that climbers, when growing, do this very markedly, the 

 end of the shoot in twiners and the tendrils or leaves in 

 those which have special holdfasts to enable them to climb, 

 describing quite wide circles in their efforts to catch on to 

 some support. Tendril-bearing plants are much less ag- 

 gressive than twiners in their struggles to climb upwards. 

 Tendrils are very sensitive, and are so constructed that they 

 can grasp and in a short time hold fast to a twig or other 

 body that may afford support. Before this happens the 

 tendril is straight, but afterwards it contracts itself spirally 

 in the most beautiful manner, thus forming an elastic 

 spring which gives a little to pressure from wind or to the 

 weight of the shoot of which it is a part. Plants with 



