50 ME. DARWIN ON CLTMBINa PLANTS. 



degree of spontaneous movement ; for in one case they certainly 

 described minute, irregular, vertical ellipses- The tendrils ap- 

 parently curve themselves spontaneously to the same side with 

 the petioles; hut the movement was so slight that it may he 

 passed over. From various causes, it was difficult to observe 

 the movements of the petioles and tendrils in this and the two 

 following species. The tendrils are so closely similar in all 

 respects to those of the following species, that one description 

 will suffice. 



Bignonia nngtds. — The young shoots revolve, but less regularly 

 and less quickly than those of the last species. The stem twined 

 imperfectly round a vertical stick, sometimes reversing its direc- 



manner 



leaf-climbers ; and this plant is in itself a leaf-climber, though 

 possessing tendrils. Each leaf consists of a petiole bearing a pair 

 of leaflets, and terminating in a tendril, which is exactly like that 

 above figured, but a little larger. The whole tendril in a young 

 plant was only about half an inch in length, and is very unlike 

 most tendrils in shape. It curiously resembles the leg and foot 

 of a small bird with the hind toe cut off. The straight leg or 

 tarsus is longer than the three toes, which latter are of equal 

 length, and, diverging, lie in the s^me plane ; the toes terminate 

 in sharp and hard claws, much curved downwards, exactly like 

 the claws on a bird's foot. The whole tendril apparently repre- 

 sents three leaflets. The main petiole (but not the two sub-pe- 

 tioles of the lateral leaflets) is sensitive to contact with any object: 

 even a small loop of thread after two days caused one to bend up- 

 wards. The whole tendrils, namely the tarsus and three toes, 

 especially their imder surfaces, are likewise sensitive to contact. 

 Hence, when a shoot grows through branched twigs, its revolving 

 movement soon brings the tendril into contact with some tw^g, and 



hours 



all three toes bend (or sometimes one alone) 



^j^ . — — __, — — — _ , -^ 



The tarsus,also,when It comes into contact with a twig, slowly bends, 

 until tlie foot is carried quite round, and the toes pass on each side 

 of the tarsus, or seize hold of it. If the main petiole bearing the 

 leaflets comes into contact with a twior. \t hkpwisp bpnrla round, 



tendril 



leaf, which is then seized. The petioles, and probably even 

 the tendrils in a slight degree, move spontaneously ; hence 

 when a shoot attempted to twine round an upright stick, both 

 petioles after a time came into contact with it, and the contact 



