CLIMBING PLANTS. 
221 
Fig. 3. Bignonia. 
It is not always the stalk of a leaf 
which is developed into the clasping 
organ ; the Bignonia leaf shown in 
Fig. 3 hears tendrils at its free ex- 
tremity. And in other plants tendrils 
are formed from flower-stalks, in which 
the flowers are not developed, or the 
whole stem of the plant or a single 
branch may turn into a tendril. In 
one curious case of monstrosity, what 
should have been a prickle on a sort 
of cucumber, grew out into a long, An unnamed speciesTom Kew. 
curled tendril. 
The family of the Bignonias is one of the most interesting 
of the class of tendril-climbers, on account of the variety of 
adaptation which is found among them. 
In the above-mentioned Fig. 3 is seen the tendril-bearing 
leaf of a species of Bignonia. The leaf bears a pair of leaflets, 
and ends in a tendril having three branches. The main tendril 
may be compared to a bird’s leg with three toes, each bearing a 
small claw. And this comparison seems apt enough, for when 
the tendril comes against a twig, the three toes curl round it 
like those of a perching bird. 
Besides the toes or tendrils, the leaf- stalk is sensitive, and 
acts like that of a regular leaf- climber, wrapping itself round a 
neighbouring 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 Tropaeolum — a tendril- climber whose young 
leaves have no tendrils, instead of a leaf- climber whose young 
climbing organs are not leaves. Thus the close relationship 
that exists between leaf and tendril- climbers is again illus- 
trated. 
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 climbing 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 towards 
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 
