THE ORCHID WORLD. 



Laelia, a sufficient amount of cinnabar 

 pigment would remain. 



In Laelio-Cattleya Mercia (flava x Schro- 

 deree) the canary-yellow colour of the La?lia 

 is not overcome by a preponderance of purple 

 pigment ; the flowers of the hybrid are 

 generally of a good yellow colour, but are 

 naturally somewhat narrow in the segments. 

 In this also improvement would be effected 

 by crossing the hybrid with C. Schroderae, 

 and thereby obtaining a greater percentage 

 of the large and better shaped parent. 



Laelio-Cattleya Olivia (Jongheana x Schro- 

 derae) IS a beautiful hybrid, the hapiiy 

 combination of the distinct yellow-ridged 

 throat of the Laelia with the orange coloured 

 throat of the Cattleya being very effective. 

 L. Jongheana and L. pumila, both dwarf 

 growing species, have the best shaped petals 

 in the Laelia genus. Another reward awaits 

 the hybridist who flowers the cross between 

 C. .Schroderae and L. pumila ; at present, 

 there is no record of its existence. 



Cattleya Schroderae in conjunction with 

 several of the highly coloured Laelio-Cattleyas 

 has yielded some excellent results, and, as in 

 otlier hybrids of three or more species, also 

 many poor ones. Those who raise the largest 

 number of plants from a seed-pod have the 

 best chance of success, for it is only when the 

 seedlings arrive at the flowering stage that 

 selection is in any way possible. It is not 

 always that the most vigorous seedlings have 

 the best flowers, some of the weakest ffrow- 

 ing ones often possess the ideal colour. 

 Thousands of seeds from every pod are never 

 grown, far less are they even germinated, and 

 how many wonderful varieties have thus been 

 lost no one dares to g\iess. 



The creation of a blue Odontoglossum is a 

 very possible event, but the entrancing idea 

 of a blue Laelia or Cattleya is likey to remain 

 unrealised. There are, however, certain com- 

 binations of pigments in the flowers of 

 hybrids which suggest the appearance of 

 blue, and it is somewhat remarkable that in 

 almost every one of these instances Cattleya 

 Schroderae has taken a part in the parentage. 

 A few Cattleyas are known to possess a. blue 

 tinge on the front lobe of the labellum, but 



the working up of these slight visible rudi- 

 ments into an ideal blue flower is almost 

 beyond the possibilities of imagination. 



DISEASE OF ORCHIDS. 



A .SOMEWHAT prevalent disease of 

 Orchids and other plants, caused by 

 a minute fungus, Thielavia fjasicola, 

 Zopf, is illustrated and described in the Kcio 

 Bulletin, 1912, p. 44. A number of C}-pripe- 

 diums, attacked by the disease, were sent to 

 Kew for investigation. 



The basal portion of each plant was soft 

 and decayed, and covered on the surface with 

 a dense, black, crusty layer consisting of the 

 Torula condition of the fungus. When placed 

 in a damp chamber at the ordinary tempera- 

 ture of the laboratory, the white Milowia stage 

 of the fungus developed within a few days, 

 and gradually encroached on the still living 

 green portion of the leaves. 



Of the symptoms of the disease in Orchids, 

 Mr. G. Massee, the author of the article, states : 

 " I have only observed the disease on culti- 

 vated species of Cypripedium, of which 

 abundant material was sent to Kew, and it was 

 stated to be present on most of the plants 

 occupying a large house. The roots are 

 attacked first, then the bases of the leaves, 

 which gradually become brown and assume 

 the condition of a soft rot, when the whole 

 plant falls over. The snow-white Milowia 

 fruit was produced in abundance when the 

 decayed portions were placed under favour- 

 able conditions for its growth. It was in all 

 probability the spores of this condition of the 

 fungus that spread the disease from one plant 

 to another in the house, the minute spores 

 being dispersed by wind, syringing, etc." 



Of the preventive measures, Mr. Massee 

 remarks : " It is practically impossible to cure 

 a plant that is once infected, as the mycelium 

 is located in the living tissue of the root, and 

 no substance is known that will check or kill 

 mycelium, without at the same time killing or 

 materially injuring the host-plant. Hence the 

 only means of checking the onslaught of the 

 fungus is by the adoption of preventive 

 measures." 



