458 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



Sterility. 



In other difficult subjects the trouble is to get pods to set at 

 all ; thus Mr. Cookson tells us that he has never been able to get 

 a pod of good seed on Dendrobium Bensoniae. (Garcl. Chron. 

 February 27, 1897, p. 134.) Many Dendrobium species seem 

 difficult to fertilise, especially the evergreen section of the genus. 



In 1892 Mr. W. H. White, for the President of the Royal 

 Horticultural Society, Sir Trevor Lawrence, Bart., of Burford, 

 pollinated over 100 flowers of D. fimbriatum, but not a single 

 seed-pod was obtained. (Orchid Bev. i. p. 17.) Mr. F. Moore, 

 of the Royal Infirmary, Liverpool, informs me that he has 

 managed to set pods on the following Dendrobiums this year : — 

 D. aureum $ x D. crepidatum roseum D. nobile $ x D. 

 Devonianum $ , D. primulinum $ x fimbriatum oculatum $ , 

 and D. clavatum $ x D. crepidatum roseum $ (in litt., Aug. 24^ 

 1897). 



The nigro-hirsute section of Dendrobriums are well known to 

 be bad setters. Mr. R. Eichel, of Bradford, tells me that for 

 eight years he has failed to cross D. formosum with pollen of 

 the deciduous section, but he has now seedlings two-and-a-half 

 months old of D. formosum $ x D. nobile from four seed-pods 

 (in litt., Aug 15, 1897). This circumstance proves to us once 

 more how misleading and unsatisfactory purely negative results 

 are, and in this there is much hope for the future. However 

 many times a cross has failed to set, we can never be sure that 

 it may not be accomplished by someone. Very trifling conditions 

 seem to affect the delicate and susceptible organs of reproduction, 

 causing apparent sterility. For instance, it is said that Epiden- 

 drum ciliare can only be fertilised with success in the evening, 

 when the flowers begin to emit their fragrant perfume. (Orchid 

 Bev. v. p. 115.) (Mr. Harry Veitch tells me that this is not 

 so with him.) Again, Mr. Eichel has found E. vitellinum 

 very difficult to set seed, and still more difficult to raise plants ; 

 but Messrs. Veitch & Sons have flowered E. radico- vitellinum, 

 and have a number of pods maturing at Langley. On the other 

 hand Messrs. Veitch have failed to set a pod on E. radicans, 

 whereas Mr. Eichel tells me he has plants up of E. radicans ? 

 crossed with pollen of E. Wallisii and Cattloya Bowringiana ; and 

 Messrs. Sander have also plants up of E. radicans ? xE. Wallisii. 

 (Orch. Bee. v. p. 801.) 



