90 TENDRIL-BEARERS. Chap. III. 



and thicken, and ultimately becomes wonderfully 

 strong, in the same manner as the petioles of leaf- 

 climbers. If the tendril catches nothing, it first 

 slowly bends downwards, and then its power of clasping 

 is lost. Very soon afterwards it disarticulates itself 

 from the petiole, and drops off like a leaf in autumn. 

 I have seen this process of disarticulation in no other 

 tendrils, for these, when they fail to catch an object, 

 merely wither away. 



Bignonia venusta. The tendrils differ considerably 

 from those of the previous species. The lower part, 

 or tarsus, is four times as long as the three toes ; these 

 are of equal length and diverge equally, but do not 

 lie in the same plane ; their tips are bluntly hooked, 

 and the whole tendril makes an excellent grapnel. The 

 tarsus is sensitive on all sides ; but the three toes are 

 sensitive only on their outer surfaces. The sensitive- 

 ness is not much developed ; for a slight rubbing with 

 a twig did not cause the tarsus or the toes to become 

 curved until an hour had elapsed, and then only 

 in a slight degree. Subsequently they straightened 

 themselves. Both the tarsus and toes can seize well 

 hold of sticks. If the stem is secured, the tendrils are 

 seen spontaneously to sweep large ellipses ; the two 

 opposite tendrils moving independently of one another. 

 I have no doubt, from the analogy of the two following 

 allied species, that the petioles also move spontaneously ; 

 but they are not irritable like those of B. unguis and 

 B. Tweedyana. The young internodes sweep large 

 circles, one being completed in 2 hrs. 15 m., and 



