2 36 ORCHIDS 



Disa. 



of seeing them some sixteen years later, \\-hen their con- 

 dition was eminently satisfactory. They had the full 

 benefit of free ventilation throughout the )'ear, and, except 

 to exclude frost, no fire-heat was used. 



During the growing season the plants should be freel)- 

 syringed overhead, and a liberal supj:)!}- of moisture 

 afforded at the roots. The shading used should be onl)' 

 sufficient to prevent scorching of the foliage during the 

 hottest parts of the clay. The potting compost should 

 consist of good fibrous peat, li\'ing sphagnum, and a liberal 

 proportion of rough sand and broken potsherds intermixed. 

 Free and ample drainage must also be provided. There are 

 instances of I), graiidijlora being grown successful!)- 

 for many years, and then suddenly failing. This is often 

 brought about after a lengthened period of dry weather. 

 Thrips plaj' ]ia\-oc in a season of this description, and as 

 an abundance of \-entilation is necessary under such 

 conditions, these pests obtain free access to the house, and 

 cjuickly attack the tender shoots, disfiguring and often 

 destroying them. Fumigation is naturall)' resorted to, 

 but the remed}- is worse than the disease, and many fine 

 batches of ]:)lants ha\-e thus been destro}'ed. No apparent 

 ill-effects will be rjbser\-ecl for a few days, but suddenh' a 

 black spotting appears on the lea\-es, and this passes into 

 the stems, and continuing a downward course, finally ends 

 in the total deca}- of the growths. If the tubers escape 

 injury fwhich is rarely the case) they commence growing 

 again after a short period ; but it takes a considerable 

 time for plants thus \\-eakenecl to regain their \'igour. 

 Where thrips are obser\-ed, the plants should be frequently 

 sprayed with weak tobacco-water or some non-injurious 

 (so far as plants are concerned) insecticide, or the plants 

 may be dipped ; but in this case great care must be 

 taken, as the growths are so brittle that they quickly 

 break should the\- come in crjntact with the sides of the 

 bath. 



The following species and h)-brids are at present in 

 commerce: 



D. grandiflora {Linn. f.). — Rootstock tuberous. Stem erect, 

 unbranched, ift. to 2ft. high, leafy. Lower leaves 6in. long, and 

 dark green ; the upper ones smaller, those near the flowers being 

 reduced to bracts. Flowers terminal, from one to ten, or even 



