66 
J. SAUNDERS—CLIMBING PLANTS 
rachis straight or nearly so. When contact with a support is 
obtained, the rachis twists and turns in various directions, some¬ 
times effecting a complete revolution in which it necessarily carries 
with it the terminal leaflet. Sometimes the petioles of leaves on 
different branches of the same plant twine round each other, thus 
securing mutual support. The peculiarities here referred to are 
common both to the British wild clematis and to the exotic species 
which are introduced into gardens. 
In the Fumitories that have come under the writer’s observation, 
the twining habit affects both the rachis of the leaf and also the 
leaflets. This has been noticed in Fumaria officinalis , a very 
common form of the Chalk area. The allied species Corydalis 
claviculata , a plant of woodlands, most frequent on sandy soils, 
illustrates the transition from leaf-climber to tendril-bearer, its 
tendrils producing diminutive leaflets. 
The exotic plant Cobea scandens, which is a favourite flower of 
floriculturists, has leaves composed of one pair of leaflets above 
which the rachis is continued as a branched tendril. 
Tendrils. —These may be either a modified branch or modified 
foliar organs. Examples of the former are furnished by vine, 
Virginia creeper ( Ampelopsis ), and white bryony, in all of which 
the tendrils are leaf-opposed, or extra-axillary. In white bryony 
the tendrils are simple; in vine and Ampelopsis they are compound. 
The growing points of the tendrils of vine possess the power of 
rotary motion for a limited period, the movement being most 
pronounced during a warm afternoon. If they secure a point of 
attachment, the tendrils speedily twine themselves round the 
support, which is succeeded by a considerable increase in size from 
the growth of woody tissue. If after several days they fail in 
securing a means of support, the organ becomes atrophied, dwindles 
in size, and eventually falls off. This peculiarity also affects the 
tendrils of other climbers, as Virginia creeper and white bryony. 
In Veitch's creeper ( Ampelopsis Veitchii ) the small branched 
tendrils are presumably affected by negative heliotropism, since 
they turn towards the support near which they are growing, and 
hence away from the incident light. The tips of the branches of 
the tendril develop small fleshy discs which adhere so strongly that 
when pulled the tendril will more frequently break than become 
detached. It is necessary that the surface up which it is desired 
they should climb should be slightly rough to enable the discs to 
adhere. They are unable to ascend a stucco wall painted so as 
to be quite smooth. A conspicuous failure under these conditions 
occurred at Putteridge Gardens, near Lilley, Herts. The tendrils 
of white bryony are unbranched; these, when they have secured 
a point of attachment, speedily contract by means of a double 
series of spirals, about one half of which turn in one direction 
and the other half in the opposite. The point of divergence is 
clearly indicated near the middle of the organ. Other illustrations 
of simple tendrils are furnished by various members of the cucumber 
tribe, to which group the white bryony belongs. 
