TEKDEIL-BEiLEEES. 103 



m 



when the stem spirally ascends a thin upright stick, but they can 

 seize any twig or branch lying beneath them ; but when the stem 

 spirally ascends a somewhat thicker stick, a slight degree of sensi- 

 tiveness in the petioles is brought into play, and they wind their 

 tendrils round the stick. In B. unguis and £. Tweedyana the sen- 

 sitiveness, as well as the power of movement, in the petioles is 

 greatly augmented ; and the tendrils and petioles are thus inex- 

 tricably wound together round thin upright sticks ; but the stem, 

 in consequence, does not twine so well : B. Tweedyana, in addition, 

 emits aerial roots which adhere to tlie stick. In B. venusta the 



structure 



gra 



spoutaneous movement ; the petioles, however, have lost their 

 sensitiveness. The stem can spirally twine round an upright stick, 

 and is aided in its ascent by the tendrils alternately seizing the 

 stick some w^ay above and then spirally contracting. In this and 

 all the following species the tendrils spirally contract after seizing 

 any object. In B. littoralis and B, Chamherlaynii the tendrils, which 

 have the same structure as in B, venusta, and the non-sensitive 



and the intemodes 



The stem, 



however, cannot spirally twine, but ascends an upright stick by 

 both tendrils, seizing it above. In B. littoralis the tips of the 

 tendrils become developed into adhesive disks. In B. speciosa and 

 B. picta we have similar powers of movement, but the plant cannot 

 spirally twine round a stick ; it can, however, ascend by clasping 

 it with one or both of its unbranched tendrils, on their own level ; 



an 



tinually inserting their pointed ends into minute crevices and 

 holes. In B, capreolata the stem twines in an imperfect manner; 

 the much-branched tendrils revolve in a capricious manner, and 

 they have the power of bending in a conspicuous manner from 

 the light to the dark ; their hooked extremities, even whilst im- 

 mature, crawl into any crevice, or, when mature, seize any thin 

 projecting point ; in both cases they develope adhesive disks, 

 which have the power of enveloping by growth the finest fibres. 



In the allied BccremocarpuB the internodes, petioles, and ten- 

 drils all spontaneously revolve together ; its much-branched ten- 

 drils resemble those of Bignonia capreolata^ but they do not turn 

 from the light ; and their bluntly hooked extremities, which arrange 



form adhesive 



ley act best when each seizes a few 

 grass, which thev afterwards draw 



