ORCHID CONFEEENCE. 



419 



Having secured the identification of each individual stud plant, 

 the next step is to ascertain its germinal constitution by breeding 

 from it. The original Mendelian method was to self the plant, but 

 recent results show that this method alone is not suf!icient to give a 

 complete analysis of the germinal constitution of a plant. In order 

 to do this it is necessary to cross-breed with it as a parent, and in cases 

 like albinism, for instance, this is the only method possible. From this 

 it is evident that the ordinary experiments in hybridization and cross- 

 breeding made by Orchid breeders are precisely what we require in order 

 to ascertain the germinal constitution of individual plants, provided that 

 each individual plant used as a parent is carefully identified for future 

 reference and use. 



Self- Sterility in Orchids. 



The question oi seMng Orchids leads us to another point which may 

 be of some interest. Eecords of the flowering of seedlings from selfed 

 hybrids are exceedingly rare in Orchids. At one time the writer thought 

 that this might be due, on the one hand, to the practical prejudice 

 against in-breeding, or, on the other hand, to the idea that nothing 

 new might be expected from selfing. Now, however, after attempting 

 to self several hundreds of different flowers of Gypriyedium and other 

 Orchid hybrids at Burbage during the past ten years, the writer has 

 come to the conclusion that self-sterility in hybrid Orchids has to be 

 seriously reckoned with, being apparently the rule rather than the excep- 

 tion For instance, since publishing my Mendelian experiments with 

 Cypripedium x ' Hera ' in 1903,* I have from time to time endeavoured 

 to self the individual F2 hybrids as they flowered, but in every case 

 but one when the pods formed they afterwards proved to be empty. 

 A few seeds, however, were secured from one pod of selfed 0. x ' Hera ' 

 punctatum, and a single Fa plant has flowered which bred true to its 

 spotted parent in so far as the spotted character was concerned. 



Oh the other hand, Mr. E. A. EolfeI has obtained a number of 

 seedlings at Kew ol selfed Epidendruni x kewense, several of which 

 have flowered, and other odd records are to be found during the past 

 twenty years, where selfed Orchid hybrids have produced plants which 

 have flowered. These cases, however, appear to be exceptional. 



In 1898 the writer | showed that sterility in hybrid Oypripediums 

 was due in certain cases to a loss of power in the pollen of hybrids. 

 For instance, species ? x species ^ produced 95 per cent, of fertile pods, 

 while species ? x hybrids ^ gave only 56 per cent. Again, hybrids $ x 

 species ^ produced 89 per cent., while hybrids ? x hybrids ^ gave only 

 59 per cent. It is possible that the same cause may be concerned in 

 the self-sterihty of Orchid hybrids generally, plus some other factor 

 unknown. 



* Hurst, C. C, " Mendel's Principles Applied to Orchid Hybrids," Journ. Roy. 

 Hort. Soc. vol. xxvii. (1903), pp. 614-24, figs. 167-69. 



t RoLFE, R, A., " Epidendriim x kewense : A Mendelian Experiment," Orch. Rev. 

 vol. XV. (1907), pp. 58, 59. [See also xvii. (1909), p. 69.] 



% Hurst, C. C, " Notes on some Curiosities of Orchid Breeding," Journ. Roy. 

 Hort. Soc. vol. xxi. (1898), pp. 485, 486. 



£ E 2 



