HYBRID RHODODENDRONS. 



243 



amongst true hybrids and crosses, it is now well known that they 

 range from zero to infinity in both cases ; but that hybrids, as 

 a rule, are more sterile than subsequent crosses. In the case of 

 the East Indian Rhododendrons, Mr. Veitch detected no differ- 

 ences in the fertility of the seedlings he raised, whether of first 

 hybrids or of subsequent combinations — the average number of 

 seeds in any pod being roughly estimated at 500, no accurate 

 measurements having been taken. 



It has been asserted that seedlings of true hybrids, which 

 resemble one parent very much, are usually very sterile ; but 

 Mr. Veitch did not find it to be so in the present instance. His 

 results, however, conformed to the rule that there was greater 

 uniformity in first hybrids than in subsequent crosses. Similarly 

 his reciprocal hybrids were, as is usually the case, very like one 

 another ; there appears to be no difference in their fertility. 



As Mr. Veitch found great difficulties in crossing species of 

 Cypripedium from the two hemispheres, so likewise attempted 

 crosses between the E. I. Rhododendrons and Sikkim or American 

 species have met with little success, though the seven species 

 utilised cross amongst themselves with great facility. 



As an illustration, Princess Royal (fig. 35) (=B. jasmini- 

 florum x B. javanicum) x B. AucManclii from Silkim (fig. 34) 

 gave rise to a small white-flowered cross called "Pearl." It 

 closely resembles Princess Alexandra (fig. 37). In fact, the 

 white male parent simply eliminated the pink from Princess 

 Royal, scarcely affecting the size of the corolla at all. 



M. Naudin found that colours were sometimes associated with 

 sterility and affinity, but nothing of the sort obtains amongst 

 these species of Rhododendron. 



On examining the pollens I found that several of the grains 

 from the true hybrids were shrivelled, or else refused to swell 

 with water. On the other hand, the pollen grains of the first 

 and subsequent crosses were all good, and swelled up vigorously 

 in water. E.g. "Hippolyta," which contains five species in its 

 constitution, is one with composite grains, and all good. 



Summary of the Effects of Colours on Crossing. 



1. The Comhination of Colours. — Reds and yellows form 

 orange, ranging from yellow-orange to scarlet -crimson. 



