TENDKIL-BEAUERS. 51 



caused still further bending ; so that ultimately both petioles 

 clasped the stick in opposite directions, and the foot-like tendrils, 

 seizing on each other or on their petioles, fastened the stem to the 

 support with surprising security. Hence this species, differently 

 from the last, uses its tendrils, by the intervention of the spon- 

 taneously moving and sensitive petioles, when the stem twines 

 round a thin vertical stick. Both species use their tendrils 

 in the same manner when passing through a thicket. This plant 

 seems to me the most efficient climber which I have examined ; 

 and it probably could ascend a polished stem incessantly tossed by 

 heavy storms. To show how important vigorous health is for the 

 action of all the parts, I may mention that when I first examined 

 a plant which was growing pretty well, though not vigorous^, 

 I concluded that the tendrils acted only like the hooks on a 

 bramble, and that this was the most feeble and inefficient of all 

 climbers ! 



Bignonia Tweedyana. — This species is closely allied to, and be- 

 haves in all respects like the last ; perhaps it twines round a ver- 

 tical stick rather better. On the same plant, one branch twined 

 in one direction and another in an opposite direction. The inter- 

 nodes in one case made two circles, each in 2 h. 33 m. I was enabled 

 in this species to observe, better than in the two preceding, the 

 spontaneous movements of the petioles : one described three small 

 vertical ellipses in the course of eleven hours, another moved 

 laterally in an irregular spire. Some little time after the stem 

 has twined round an upright stick, and is securely fastened to 

 it by the clasping petioles and tendrils, it emits at the base of 

 its leaves aerial roots, which curve partly round and adhere to 

 the stick ; so that this one species of Bignonia combines four 

 different methods of climbing, generally characteristic of distinct 

 plants, namely, twining, leaf-climbing, tendril-climbing, and root- 

 climbing. 



In the foregoing three species, when the foot-like tendril has 

 caught any object, it continues to grow and to thicken, and ulti- 

 mately it becomes wonderfully strong, in the same manner as we 

 have seen with 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, like a leaf in autumn from the stem, and 

 drops off. I have seen this process of disarticulation in no other 

 tendrils, but when imcaught they soon wither away. 



Bignonia venusta, — The tendrils are here considerably modified 



e 2 



