CLIMBING PLANTS. 643 



Besides the toes or tendrils, the leaf-stalk is sensitive, and acts like 

 that of a regular leaf-climber, wrapping itself round a neighboring 

 object. 



In some cases the young leaves have no tendrils at their tips, but 

 clasp with their stalks, and this is a case exactly the reverse of Tro- 

 pceolum a tendril-chamber whose young leaves have no tendrils, in- 

 stead of a leaf -climber whose young climbing organs are not leaves. 

 Thus the close relationship that exists between leaf- and tendril- 

 climbers is again illustrated. 



This plant also combines the qualities of another class of climbers, 

 namely, twiners, for it can wind spirally round a support as well as a 

 hop or any other true twiner. Another species (B. Tweedyana) also 

 helps to support itself by putting out roots from its stems, which 

 adhere to the stick up which the plant is climbing. So that here are 

 four different methods of climbing twining, leaf, tendril, and root 

 climbing which are usually characteristic of different classes of climb- 

 ing plants, combined in a single species. 



Among the Bignonias are found tendrils with various curious kinds 

 of sensitiveness. The tendrils of one species exhibit, in the highest 

 perfection, the power of growing away from light toward darkness, 

 just the opposite to the habit of most plants. A plant, growing in a 

 pot, was placed so that the light came in on one side. One tendril 

 was pointing away from the light, to begin with, and this did not 

 move ; but the opposite tendril, which was pointing toward the light, 

 bent right over and became parallel to the first tendril. The pot 

 was then turned round, so that both pointed toward the light, and 

 they both moved over to the other side, and pointed away from the 

 light. In another case, in which a plant, with six tendrils, was placed 

 in a box, open at one side, all six tendrils pointed like so many 

 weathercocks in the wind all truly toward the darkest corner of the 

 box. These tendrils also showed a curious power of choice. When 

 it was found that they pref erred darkness to light, it was tried whether 

 they would seize a blackened glass tube, or a blackened zinc plate. 

 The tendrils curled round both these objects, but soon recoiled and 

 unwound with what, my father says, he can only describe as dis- 

 gust. A post with very rugged bark was then put near them ; twice 

 they touched it for an hour or two, and twice they withdrew ; but 

 at last one of the hooked tendrils caught hold of a little projecting 

 point of bark ; and now it had found what it wanted. The other 

 branches of the tendril quickly followed it, spreading out, adapting 

 themselves to all the inequalities of the surface, and creeping into all 

 the little crevices and holes in the bark. Finally a remarkable change 

 took place in the tendrils : the tips which had crept into the cracks 

 swelled up into little knobs, and ultimately secreted a sticky cement, 

 by which they were firmly glued into their places. This plan of 

 forming adhesive disks on its tendrils is one which we shall find used 



