ORCHID CONFERENCE. 



443 



your attention to the plant Cattleya Trianae ' Mrs. Edward Sond- 

 heim.' The flowers of this plant when I first saw them were pure 

 white, and, as such, received a F.C.C. from the E.H.S. 



The drawing which was made of it at the time shows it as a pure 

 albino, but it has since flowered coloured. 



How, then, is one to account for this reversion towards the type? 

 I believe that the colours one sees in Orchid flowers are produced upon 

 the surface of the flower by the chemical action of light and air. 

 The plant contains selected coloured sap ; this is drawn up through 

 the stem to the bud, and is split up along the veins upon the surface 

 of the flower. This sap by the process known as ripening is made 

 more or less responsive to the action of oxidation by light and air, 

 and the varying richness of the colours obtained in the flowers depends 

 upon the amount of light and air admitted to the plant during the 

 ripening period as well as the final stages of the flowers' development. 



When a plant produces flowers of richer colours than previously, 

 we say this is due to good cultivation," and so it is. The riper 

 the plant, and the more light and pure air available for the cultivators' 

 judicious use, tine richer will the colour sap be, and the more noticeable 

 will be the chemical change of the sap in the veins upon the surface of 

 the flower. 



A plant which has flowered white one year, and slightly flushed 

 the next, may be made to flower white again by opening the bud 

 in the dark, and so preventing the light from producing a chemical 

 change in the sap. 



I believe that plants which flower white one year and flushed 

 another year possess in themselves a small quantity of colour sap, 

 which is observed in the colour of the flower only when sufficient 

 oxidation has taken place. 



Only those plants which flower white year after year under good 

 cultivation may be looked upon as "fixed," and are the only safe 

 plants to use for producing white progeny. 



When albinos (so-called) will not intercross to produce white, 

 I would attribute the reason to one or both of the parents containing 

 colour sap, and by the same reasoning I commit myself to the belief 

 that all true albinos will intercross with their own class to produce 

 white. 



In closing this paper I would ask all who are interested in Orchids 

 to use their endeavours to stop the careless, misleading, and too 

 frequent use of the word " alba" as applied to plants which have no 

 right to the description. 



By this I do not merely mean flowers with coloured lips, but 

 I particularly refer to those flowers which are distinctly flushed ^ith 

 colo'Ur on the sepals and petals, and are still labelled " alba." 



To record such plants as white make it very difficult to arrive at 

 logical conclusions, and is particularly unfair to those who by their 

 writings are endeavouring to assist the raiser, and who must have 

 accurate data from which to work. . , . . . . . . ■ 



