8 PREFACE. 
In another place in Bootan (Pass of Rodoola, 12,000 fect), Mr. Griffith speaks of Rhododendrons as the only vegetation at 
the summit, and in the descent he traversed a “ region of Rhododendrons.” 
It is not our intention, nor is it required by the nature of this little treatise, to enumerate all the Rhododendrons that 
are known in books: suffice it to say, that (exclusive of some Azaleas of Linneus) thirty-two are distinguished by 
De Candolle in the seventh volume of his Prodromus, published in 1839; and enough has been here stated to show that the 
maximum of the species exists in Asia; for, commencing with Borneo and other Malayan islands in the tropics of the 
southern hemisphere, and proceeding north, we find them recorded in the mountain regions of all the intervening countries 
that have been botanically investigated, even to northern and extreme arctic Siberia. As we proceed westward into 
Europe, they gradually disappear, one only inhabiting Sweden and Norway (2. Lapponicum), and that seems not to extend 
to the western coasts. 
In the vast continent of North America, the cool hilly grounds, with moisture, of the middle and southern states, 
yield only 2. maximum (which, however, is found also in Canada), R. macrophyllum, Don, confined to the west side of 
the Rocky Mountains, #. Catawbiense and R. punctatum, which two have a very limited range. The anomalous 
LR. albifiorum, with white flowers and deciduous leaves, is only seen in the Rocky Mountains, about lat. 52°. As might 
be expected, in the alpine and arctic Perens the northern European kinds appear; for example, 2. Lapponicum has been 
ietected on the White Mountains, Massachusetts, on the summit of Mount Mary, Essex County, New York, at an elevation 
of 5,400 feet on the Rocky Mountains, in Labrador, and along the coasts of the Polar Sea; while in Behring’s Straits, the 
. Kamschaticum again appears. No species grows in Mexico or near the coasts of Oregon or California, and none in 
the isthmus of Panama. Throughout the whole of Africa’ and Australia, the genus is unknown ; and it will be observed 
that it only enters the southern hemisphere through the medium of the Indian Archipelago. 
When it is borne in mind that, as above stated, Mr. Griffith, in an excursion to one mountain in Bootan, detected eight 
species,” and that the author of the present work, during a very limited sojourn in Sikkim, and with little means of prosecuting 
extensive researches, owing to the nature of the country and the hostile feeling entertained towards the English by the 
Rajah, yet collected and described eleven species, of which nine were new, it may, I think, be fairly conceded that if the 
maximum of Rhododendrons be in Asia, their head-quarters are on the lofty ranges of the Eastern Himalaya, where the 
mild and moist atmosphere is eminently suited to their habit.—Ep. 
1 Boissier, indeed, in his Voyage Botanique en Espagne, says of the R. Ponticwm :— Hab. verosimiliter in Atlante,”—but I know not 
upon what authority. 
* How far these species may accord with those of Sikkim, or whether any will do so, cannot be determined, until the Hon. the E. 1. C. 
shall be pleased to unlock the treasures contributed by Mr. Griffith to the Herbarium stores in the possession of the Company; and there is 
now happily a prospect of this long-wished-for event taking place. The few Rhododendrons that have been edited by Dr. Wight we know to 
be very different and of peculiar interest. 
