IIQ CLIMATE AND VEGETATION OF 



blossoms than I ever saw it to have in the Himalaya, but of a paler 

 hue by far than any of the red-coloured series in Sikkim, except 

 R. antJiopogon, — judging from colour alone, I should not have 

 recognised it. i>Iay is its flowering season in its native locality, 

 and a purplish red the colour I have been accustomed to see it. 



Sikkim climate as compared with London. — The colder win- 

 ters and warmer summers are the prominent differences of the 

 London climate, as the following comparison shows : — 



The extreme Darjiling data given here are not low enough for 

 the minimum, or high enough for the maximum ; but they give a 

 sufficient approximation. At 10,000 to 11,000 feet, where most 

 species of rhododendrons grow, the climate in its main features 

 of great extremes approaches nearer to the English ; but tlie 

 mean temperature (40°) is too low. Our summers are nmch too 

 hot for the plants of that elevation, and our winters being too mild, 

 they make shoots earlier in spring than in the Himalaya, which 

 are cut off by frosts in April. Though the temperature is more 

 uniform in Sikkim, it presents one curious anomaly, which is, 

 that an accession of 8° of temperature occurs in March, above 

 February, the parallel of which does not occur till June in Eng- 

 land, which is 8° warmer than May. This brings the rhodo- 

 dendrons so early into flower at 7000 feet, and keeps the radiating 

 thermometer always above freezing for the rest of the spring. 



Again, there is in London nearly 20° of average difference 

 between the day and night temp, of April, and 22° in May, — 

 months wherein 15° and 13° are the corresponding Darjiling 

 differences. This is a very powerful obstacle to the cultivation 

 out of doors of many otherwise very hardy Himalayan plants, 

 which are impatient of sudden changes, and incapable of bear- 

 ing sudden, sharp frosts in March and April. 



As the flowering season advances and fruit-setting comes on, 

 the temperature in Sikkim becomes more markedly uniform, the 

 mean difference between day and night being, in May, 13°; 

 June, 11°; July, 10°. Li London it is not so: May, 22°; 

 June, 21"6° ; July, 21*6°. Turningagain to the autumn solstice, 

 the sudden fall of temperature occurs both in Sikkim and Lon- 

 don ill November, and amounts in each to upwards of 7° ; but 

 whereas the difference between day and night is increasing in 

 Sikkim, it decreases in London, a circumstance which may affect 

 ^Jje rijjening of seed, by checking tli(> vegetative organs. 



