1 6 THE BOOK OF CLIMBING PLANTS 



to be entirely covered by the plants. A simple arch 

 of four upright poles with cross ones will do perfectly 

 well for many things. 



The pergola is rapidly becoming a favourite erection in 

 gardens and owes its chief interest and beauty to the 

 climbers which are trained to its pillars and shade its 

 pathway. The pergola might be introduced into more 

 gardens with advantage, but it ought always to be in 

 such a situation that it forms either the entrance to a 

 part of the garden or a pleasant feature of some path 

 which leads to a definite object, instead of being, as 

 some are, without an apparent raison d'etre beyond that 

 of affording a purely scenic effect. The structure 

 of the pergola will depend upon the means of the 

 owner, and may be an elaborate stone or brick erection, 

 on which are laid cross beams of wood or trunks of 

 trees to which the climbers are attached. Or it may 

 be a simple erection of larch or other poles with others 

 laid lengthways and crossed by similar poles. Light 

 iron pillars bearing timbers can also be used, but the 

 wooden pergola is generally the prettiest and the most 

 welcome to the climbing plants. The uprights may 

 be bedded in concrete in the soil or have their ends 

 tarred or charred to preserve them. 



For a pillar, nothing looks so well as an unbarked 

 tree of moderate thickness, but iron ones, either plain 

 or formed of lattice work, are sometimes used. Other 

 more or less elaborate contrivances, such as a stout 

 central pole with chains radiating from it, are also 

 formed. 



Climbing plants are subject to the attacks of various 

 pests, both in the open and under glass. In the open 

 these enemies are usually worse on a wall than else- 

 where, and the less it is covered with foliage the greater 

 the difficulty in keeping the plants free from them. 



Aphides are the causes of much annoyance and loss, 



