Encyclopaedia of Gardening 317 



plants as Sedums, Pinks, Sempervivums, Wallflowers, Corydalises, 

 Arabises, Aubrietias, Alyssum saxatile, Cerastiums, Valerian, and 

 encrusted Saxifrages are established merely by sprinkling a few 

 seeds into chinks; in others spikes are driven into the wall to 

 support small flattish stones, on which plants are established. A 

 steep bank may be made beautiful by making a rough wall of un- 

 mortared stones against its face, and here all the plants named 

 above, with Campanulas, Hutchinsia Alpina, and many other 

 pretty things, will thrive. Walls are also adorned with fruit and 

 with climbing plants. See Fruit and Climbers. 



Walnut. See Juglans. 



Wardian Case. This is useful for sending plants from abroad, for 

 it can be kept close, so that delicate plants are not injured by fre- 

 quent changes of temperature. We occasionally 

 see it in a room window, but less frequently than 

 of yore. It was a favourite device of our fore- 

 fathers to block the approach to a window with 

 a large plant case and live in an atmosphere of 

 mustiness. Given abundance of space a Wardian 

 case planted with ferns has good claims to a 

 place in a shady window. Provision should be 

 made for drawing off surplus water. 



Wasps. When present in large numbers these 

 are a great trial to gardeners; they enter fruit 

 houses and do a good deal of damage. It is a 

 mistake to put bottles of syrup in or near the 

 houses with the object of drawing the wasps 

 away from the fruit, as the sugary preparation 

 attracts wasps to the garden. Queen wasps 

 should be killed when they appear in the spring. 

 Pieces of fine canvas may be put over the venti- 

 lators. Nests may be sought for, marked, and attacked at night 

 with boiling tar, or a lighted squib of gunpowder and sulphur may 

 be pushed in and the hole stopped with damp earth after the 

 explosion in order to prevent the fumes from escaping. 



Water Aloe, Stratiotes aloides. 



Water Archer, Sagittaria sagittifolia. 



Water Avens, Geum rivale. 



Water Bean, Nelumbium. 



Water Cress. See Kitchen Garden and Nasturtium. 



Water Flag, Iris Pseudacorus. 



Water Gladiole, Butomus umbellatus. 



Watering. The watering of plants has a great bearing on their 

 health, particularly if they are in pots, and should be studied by 

 cultivators. It may be assumed that every plant needs water when 

 it is growing, but it must not be assumed that it needs the same 

 amount every day. A plant gets rid of more moisture by leaf- 

 evaporation on a hot, dry day than on a cool, wet one, consequently 

 water is more likely to be needed under the former than under the 

 latter conditions. Signs of want of water are: flaccid growth, soil 



A TRAP FOR WASPS. 



One handlight is fitted 

 over another, with 

 a hole in the lower 

 one. A saucer of 

 sour beer or syrup 

 draws the wasps in. 



