876 General Notices. 



by Sir William Hooker, Reeve, Bentham, and Reeve. In the work before 

 us we have eleven species described, and nine of these are new, R. barba- 

 tum and R. arboreum being the exceptions. The most remarkable are R. 

 Dalhonsia;, R. argcnteum, and R. Falconeri. The individual flowers of 

 R. Dalhousia? measure five inches from the base of the florets to the ex- 

 tremity, and four inches and a quarter across the mouth. The leaves of R. 

 argenteum measure eleven inches in length, and upwards of three in breadth. 

 The leaves of R. Falconeri measure one foot in length and six inches in 

 breadth. R. barbatum has endured the winter at Chester. It is found at 

 an altitude of 10,000 feet. This is not always a certain criterion of hardi- 

 ness ; it is, however, an approximation, and if so, then R. Campbelliae, ar- 

 genteum, and Falconeri, are all found at 10,000 feet of altitude, and will, 

 at least, be what is called half-hardy. 



Darjeeling, in the Sikkim portion of the Himalaya, is the native country 

 of the plants figured in the splendid work before us, and is situated in lati- 

 tude 27 deg. north, and in the longitude of Calcutta, distant from the latter 

 place 380 miles, and at an altitude of 7,200 feet. The mean temperature 

 of the year is given at 55 deg. Fahrenheit. The mean temperature of 

 every month is also given, to which we add, by way of comparison, the 

 mean of the last eight years for London, viz., 1841 to 1848, inclusive, the 

 result of observations taken every two hours : — 



January, 



February, 



March, 



April, 



May, 



June, 



These columns of figures point to the important fact with which every 

 gardener is familiar, namely, that spring and not midwinter is the season of 

 trial, not only to Indian Rhododendrons, but to very many other half-hardy 

 plants from India, South America, &c. &c. It will be seen that, in Jan- 

 uary the mean temperature of Darjeeling is but 4 deg. higher than in the 

 counties of Middlesex and Surrey ; but, in March, we have the unfavorable 

 difference of 12 deg., and again in Autumn, October for example, our tem- 

 perature is 10 deg. below that of the " head-quarters" of the Indian Rho- 

 dodendrons, while, as at midwinter, as we have seen, and at midsummer, 

 we have the unimportant difl^ercnce against us of 4 and 3 deg. respectively. 

 Here we have a solution of the cause of our want of success in cultivating 

 tender plants in the variable climate of Great Britain. Our springs are 

 late, and cold, and changeable. Even this morning, April 18, the ther- 

 mometer indicated, in the garden of the Royal Botanic Society in the Re- 

 gent's Park, 9 deg. of frost, within two or three degrees of being as low as 

 it has been at any previous time during the past winter. And, again, the 

 temperature of our autumns differs greatly. October indicates a difference 

 of 10 degrees against us. Thus we see that, while the winters and the 



