THE ASSERTIVE PLANT 



^37 



THE HUGE LEAVES OF THE SOUTH AMERICAN GUNNERAS COVER IN A LARGE AREA. 



the case. As a rule, the tendril is not 

 content with merely looping itself once 

 round the support, but, in order to 

 make quite sure that there can be no 

 shpping away, doubles or trebles the 

 circles. When the attachment has been 

 rendered quite secure, the strange spiral 

 twisting comes into operation. As a rule, 

 the turning goes on in one direction for 

 half the length of the tendril, and in an 

 opposite way for the remaining half. 



This coihng busmess is very interesting 

 to watch, and is started with the for- 

 mation of a small crank-hke process, 

 which continues to make complete revolu- 

 tions, swinging downwards and upwards 

 with the greatest regularity. As it does 

 this, the tendril is, of course, coiled on 

 either side of the bent portion, in one 

 direction on one side, and in an opposite 

 direction on the other side. When the 

 coiling is completed the small crank-hke 

 part will appear as a Httle straight section 

 between the two spiral portions. At 

 times it is to be nf)ticed that tendrils w ill 

 develop several series of spirals, and thus 

 there may be two or three of the alter- 

 nating portions. The spiral conformation, 



of course, very much tends to strengthen 

 the organ, whilst at the same time it 

 secures to it a certain springiness that 

 will allow a "give" when the plant 

 strains in rough weather. 



Not a few plants climb upw-ards by 

 pressing into service their leaf-stalks ; 

 of these, the garden Nasturtiums and the 

 Wild Clematis are examples. Both these 

 species, particularly the latter, contrive 

 to rise to a considerable height by twist- 

 ing their leaf-stalks round the nearest 

 support. The Ivy has resorted to a 

 still more curious method, and is able 

 to attach its stems to trunks of trees 

 and other supports, by means of its 

 ad\'entitious roots which are so freely 

 produced. These processes serve the 

 double office of chmbing organs and also 

 as means of imbibing water ; indeed, in 

 very moist weather the ivy wiU often 

 send out quantities of the wiiite fila- 

 ments on the side of the stem which is 

 not attached to the support. Finally the 

 commtm l^ramble scrambles upwards by 

 means of the bent hooks with which its 

 stems aliound. These enahli' the plant 

 to catch hold uf any surroumUng objects. 



