THE MOST USEFUL ORCHIDS 163 



deriana has flat flowers five inches broad. The latter has stout, 

 large leaves, while V. Hookeriatia has slender terete leaves. 



Most of the Vandas require a high temperature and a moist 

 atmosphere, but when new leaves cease to form for the season, and 

 the tips of the roots become sealed over, a much reduced water 

 supply will suffice, although, as the species are all evergreen, 

 absolutely dry conditions at the roots must not be permitted. 

 Potting should be done only when the condition of the rooting 

 material or the increased size of the plant renders such an operation 

 imperative. The new year is the best time for re-potting, and if 

 this is not necessary the surface of the rooting material should be 

 removed and new sphagnum given. In the course of time Vandas 

 lose some of their lower leaves and become " leggy " ; when this 

 is the case, the lower part of the stem and roots should be cut away, 

 as there will be plenty of roots from the part of the stem above the 

 pot to carry the plant well after re-potting. 



The roots are brittle, and great care must be taken to prevent 

 injury to them. It is a good plan to crock the pots two-thirds of 

 their depth, inserting a stout stick as the crocks are placed in 

 position, for the purpose of keeping the plant upright and secure. 

 Then place a layer of sphagnum over the drainage, and carefully 

 work the roots of the plant into the pot. Fill in among the roots 

 with smaller, clean crocks, to within an inch or so of the rim of the 

 pot, and finish off^ with a thick layer of live sphagnum, slightly 

 mounded up to the stem of the plant. A good watering with 

 tepid water should follow potting, and shade from sunshine must 

 be afi^orded until the plants have re-established themselves. It 

 should, however, be remembered that Vandas do not require the 

 heavy shading that Aerides do. From March to the end of 

 October the temperature should range from ()^ to 70 degrees at 

 night to from 70 to 85 or 90 degrees by day, according to the 



