14 FLOWERING PLANTS 
Leaflets modified into tendrils occur in many of the Le- 
guminose, especially Vetches. 
Aerial roots modified into tendrils occur in the Vanilla. 
The two British hook-climbers are the Blackberry (Rubus) 
and the Goose-grass (Galium). The hooks with which they 
are furnished are outgrowths of the outer skin, and materially. 
help the plant in catching hold of the shrub or bush. This 
may be easily seen if one tries to separate a blackberry stem 
from the hedge on which it is twining. 2 | 
The best known root-climber in England is the Ivy, the 
roots of which penetrate so far into the crevices of walls as 
even to cause them to crumble away in course of time. In 
the tropics, some species of Ficus grow round trees by means 
of their roots, clasping them in a close embrace which may 
injure and even kill them. 
It is interesting to inquire of what advantage it is to a 
plant to be able to climb. It is, no doubt, by means of their 
power of climbing that many plants secure enough light for 
their development. Supposing that a bramble ant not make 
its way to the top of a hedge, or of the shrub with which it 
came in contact, it would not be likely to get enough light for 
the perfection of its fruit. In the tropics to be able to climb 
so as to reach the light is a very important matter, for there 
trees are mostly evergreens, and many plants, unless they had 
the power of climbing, would be condemned to live in per- 
petual shade ; in England, on the other hand, many herbs in- 
habiting woods flower before the leaves come out, and thus 
get enough light and warmth to bring their fruit to perfection. 
Kerner suggests that tendril-bearing stems have an advantage 
over twining stems. They reach the same height above the 
ground, he thinks, with less expenditure of material ; the twin- 
ing stem of the Scarlet-Runner when it has climbed a metre 
measures 13 metres, whereas a Pea at the same height above 
the ground measures only a metre. 
(b)Insectivor-  Insectivorous plants usually grow in soils poor 
ous Plants. in nitrogen ; they therefore get their extra nitro- 
gen from the dead bodies of the insects they capture by means 
