IT has been well remarked by the illustrious Wallich, (the Father of Nepalese Botany,) that in Nepal the genus Rhododendron claims the highest rank amongst the plants of that rich kingdom. From the proximity of Sikkim to Nepal, a similarity in the botanical features of these countries might be expected; and also that the difference should rather exist in individual species than in the genera or higher groups. The outline of the two countries is very similar, their latitude the same, so is their geology, and the difference in climate is slight, and only evident in the increased humidity of the eastern region. Rhododendrons are distributed in Sikkim as they are in Nepal, crowning those sub-Himalayan hills which attain 7,000 feet of elevation, and at a still greater altitude increasing in number of species and individuals: some species being replaced by others which have no greater, perhaps less, apparent adaptation for resisting vicissitudes of climate, and yet accompanying several of the more local kinds throughout the elevations they severally attain.
I. As is frequently the case with large genera, one or more species, distinguished by peculiarity of distribution, often present some anomalies in botanical or other characters, whether in the unusual habit, mode of growth, or singular outline, colour, or more important feature. So it is with the Sikkim Rhododendrons. R. Dalhousiae, the only one found so low as at 7,000 feet, and thence upwards for 3,000 feet more, differs from all its congeners of Northern India in its epiphytal mode of growth, (1) its sweet-scented flowers, slender habit, whorled branches, and in the length of time during which it continues in bloom. It is much the largest-flowered species with which I am acquainted, and has more membranous leaves than any of the others. With all these striking anomalies, it does not, however, present one character of calyx, corolla, stamens, or pistil, entitling it to separation from the genus. In possessing a large foliaceous
(1) In Sikkim, Vaccinium offers a parallel case. The V. serpens (?), an epiphyte on very large trees, inhabits a much lower level and ranges through many more feet in elevation than any of its congeners. [In Borneo it will be remembered that Mr. Low discovered epiphytal Rhododendrons; and Mr. William Lobb, several in Java. En.]
calyx, it is one of the most perfect plants of the whole, and in its characters of flower and fruit is far more closely allied to the typical or scarlet-flowered group, than is the section to which the following belongs.
II. Rhododendron Falconeri, a white-flowered species, is eminently characteristic of the genus in habit, place of growth, and locality, never occurring below 10,000 feet. On the other hand it is peculiar in its ten-lobed corolla, numerous stamens, and many-celled ovary, superb foliage and many-flowered capitula. This multiplication of parts and developmentof foliage and trunk give it a striking appearance; but there is an almost total absence of calyx, an organ sufficiently evident in other species. It is allied to a species discovered by the lamented Griffith in Bootan, the R. grande, Wight, published in the Calcutta Journ. Nat. Hist. vol. viii. p. 176, [and since in Dr. Wight's Icones, vol. iv. p. 6. t. 1202].(1)
III. A third white-flowered group contains but one Sikkim species, the R. argenteum, a very conspicuous tree at an elevation of between 8,000 and 9,000 feet. In beauty of foliage it nearly equals the last mentioned (R. Falconeri), and the flowers are larger than in any but R. Dalhousiae, and of the same form as those of the scarlet group; the stamens are of the normal number, but the ovarium is many-celled. Though evidently distinct, this species combines the characters of most of the other groups. In size of flower and colour, as already observed, it resembles R. Dalhousie,as it does in its unusually membranous leaves (2) ; in the colour of the flower, size of foliage, small calyx, and many-celled ovarium, R. Falconeri;-while the number of stamens, general habit, silvery under-surface of leaf, &c., connect it with R. arboreum. (3)
IV. A singular set includes the dwarfish kinds to which R. cinnabarinum and R. Roylii belong. The flowers are small, the corolla is subcoriaceous, narrowed at the base of the tube, and its colour is a peculiarly dirty brick-red, somewhat iridescent with blue in bud, and its lobes are rounded, subacute, not notched or wrinkled. The calyces are small, coriaceous, and squamous in both; in one the lobes are remarkably unequal. In the number of stamens, cells of the ovarium, &c., they agree with the usual characters of the genus.
V. Of the normal or typical group, indicated to be such by the number of species it contains, by the prevalence of scarlet flowers, uniformity of corolla and number of parts, there are two subdivisions: one has a fully developed calyx,in the other the calyx is very small and coriaceous. R. lancifolium and R. barbatum represent the former section, in both of which that organ is as conspicuous as in R. Dalhousiae. R. arboreum, R. Wallichii, and R. Campbelliae, belong to the latter section. The species of this group known to me are all trees, of contracted range and gay flowers.
VI. The little R. elaegnoides may be classed in another group: it is a very alpine plant, of which I possess only the foliage and fruit. Its scaliness (a character which seems most conspicuous in the smaller and more alpine species) allies it to R. cinnabarinum, but it is apparently single-flowered and calyculate.The sub-Himalayan mountains are surely the centrum of this truly fine genus, distinguished by the number and variety of its species and groups, by the great size and eminent beauty of several, which form conspicuous features in the landscape over many degrees of longitude, through a great variety of elevations, and clothe a vast amount of surface.
(1) From this figure and description it wil be seen, that although in many respects near R. Falconeri, especially in the dense many-flowered capitulum, smallish many-cleft corolla, numerous stamens and cells of the ovary, yet that it is quite distinct in the smaller cuspidate leaves,white and scaly beneath, and in the deeply ten-lobed corolla.
(2) The term membranous is of course used comparatively here; in no species is the foliage truly so,-- less coriaceous were the better,though more cumbrous, term.
(3) Dr. Hooker had here stated of R. argenteum, that R. Grifithianum, Wight, in Calcutta Journal of Natural History, vol. viii. p. 176, is probably a close ally of this; but that has since been published in Dr. Wight's Icones Plant. Indim Orientalis, vol. iv. p. 6. .1201, and proves to belong to, or rather to constitute, a very distant section, having very lax racemose flowers, a nearly entire, spreading, scutelliform calyx (quite unlike that of any other species), many (15 ?) stamens, and ten cells to the ovary. It is a native of Bootan. ED.
The Neelgherries, Ceylon, and the Malay Archipelago contain, each, some species which prove the affinity of their Floras to that of the Himalaya. The same is the case with the great mountains of Northern Asia, Central, Southern, and, especially, Eastern Europe, the Ural, and Pontus. The genus extends even to the Polar regions, diminishing in the size of the species and number as we recede from the Himalaya: in North America they appear again, though under a very different aspect from that they present on the subtropical mountains of Asia. Wide though this distinction is, it is far from uniform, the Himalaya itself offering most remarkable anomalies. My friend Dr. Thomson (now engaged in a botanical mission to Thibet) informs me that the genus is not found in Cashmere; nor, during all the wanderings of that intrepid and indefatigable naturalist in the Trans-Sutledge Himalaya and Thibet, has he met with one representative of it. He detected, indeed, in the country south of the Chenaub, both the R. arboreum and R. campanulatum, and which is probably their western limit.
In North-west India, the genus Rhododendron is first seen on the Kunawur hills, and advancing east, follows the sub-Himalayan range for its whole length, the species increasing in number as far as Sikkim and Bootan; thence the genus is continued to the Mishmee hills, the eastern extremity of the range, crossing the Brahmaputra to that lofty range which divides the water-shed of the Irawaddi from that of the Brahmaputra.Though scarcely found, throughout this long line of upwards of 1,200 miles, below 4,000 feet, the Rhododendrons still affect a warm and damp climate, where the winters are mild. The English naturalist, who is only familiar with the comparatively small hardy American and European species, would scarcely expect this. A certain degree of winter-cold and perpetual humidity is necessary; but the summer-heat is quite tropical where some of the genus prevail, and snow rarely falls and never rests on several of those peculiar to Sikkim.
R. arboreum, according to Captain Madden, inhabits various localities between 3,000 and 10,000 feet: this is in Kamaoon, where, of course, the genus would descend lowest; and the range is incomparably greater than that of any other species, at least of those found in Sikkim. (4) Dr. Griffith, after extended wanderings in Bootan, gives the limits of the genus in that country as between 4,292 and 12,478 feet, which is a lower level by 3,000 feet than they are known to descend to in Sikkim. In the extreme east of Assam, where the Himalaya itself diverges or sends lofty spurs to stem the Brahmaputra, on the Phien Pass to Ava, Rhododendrons ascend from 5,400 to 12,000 feet, to the upper limit ofarboreous vegetation, and perhaps still higher. During my limited excursions in Sikkim, I gathered eleven species (and I believe that more exist), a greater number than Griffith obtained in Bootan; so that I cannot but regard this longitude as the head-quarters of the genus in the Himalaya, and that chain as the especial region of the genus in the Old World. Here too I may remark (as is the case with the Coniferae of Tasmania and Cacteae of Mexico), the species are most limited in habitat, where, numerically, the genus is the largest, the R. arboreum, however, having a much wider range than any other species found in Sikkim.
(4) Dr. Hooker had here inserted "where R. arboreum is unknown," that is, in Sikkim. But one of his own excellent figures, sent home as representing a new species, is, I have no hesitation in saying, the true R. arboreum, coinciding entirely with the original figure of Sir James E. Smith (Exotic Botany, Tab. 6), and with original specimens given me by the same distinguished botanist and existing in my own Herbarium. Nor need we be surprised that Dr. Hooker should have fallen into this error, with few books and no authentic specimens to consult; especially when it is borne in mind that his eye had been accustomed to the plants that pass under that name in our gardens, but which have been so hybridized by cultivators, either to increase their beauty or with the intention of rendering the offspring more hardy, that an original plant or tree of Rhododenderon arboreum is almost as rare in England as is the normal single-flowered state of the Corelorse(Kerria) Japonica. Let it be further observed that other distinguished Botanists have confounded distinct species with the R. arboreum: I allude especially to the plant so called by Dr. Wight of the Neelgherries (Icones Plant. Ind. Orient. tab. 1201), which is the R. Nilagiricum of Zenker (Plant. Nilag. cum Ic., and of Bot. Mag. tab. 4381). No one who compares native specimens of these two plants can have any hesitation in pronouncing them distinct. Ed.
Westward again, as far, indeed, as the western termination of the Himalaya, the species descend lower than in Bootan: an anomalous fact, for which, in our ignorance of the contrasting features which may distinguish the Eastern from the Central Himalaya, I can only assign conjectural causes. Among these may be the proximity of the ocean to the Sikkim portion of the range, and the presence of heavy mountain-masses covered with winter, and even perpetual, snow, to the south and cast of the upper extremity of the Brahmaputra, whereas the genus is found nearly 2,000 feet lower than in Sikkim. The descent of the snow line in Upper Assam to 14,000 or 15,000 feet, is no doubt due to the same causes, and this is a most remarkable fact. Uniformity of temperature, excessive humidity, and a broken surface, produce the same effect here as in the high southern and antarctic latitudes, -- favouring the formation of snow and its permanence, and also extending the range of tropical forms upwards to a greater elevation, and the descent of temperate or arctic forms to a lower one; of which no stronger proof can be required than the descent of Rosaceae and Ericeae, and the great elevation which Rafflesia, Balanophora, and other eminently tropical genera, attain on the Himalaya. Too much stress cannot be laid upon this fact, that the snow-line ascends with the latitude on the Himalaya, from 14,500 feet at its south-east extreme in Upper Assam, south of the Brahmaputra, lat. 27' N., to 20,000 feet at itsnorth-west extreme in the regions near and beyond the Sutledge, in lat. 360 and 37' N. Had the level of perpetual snow remained uniform throughout these 600 miles of northing, then climate would have only annihilated the effect of distance from the equator. But if we allow that, ceteris paribus, a degree of latitude is the index of a change of 300 feet in the snow-line, we must also allow that the limit of perpetual snow is 8,000 feet lower in Upper Assam thanits height on the Sutledge Himalaya would indicate, being 15,000 instead of 23,000 feet; and, vice versd, that if 14,500 is that limit at Assam, as determined by latitude alone, in Kunawur we should have it at 11,000 instead of 20,000. Only four species, R. Dalhousiae, R. Campbelliae, R. argenteum, and R. arboreum grow near Darjeeling. The second and fourth form scattered bushes at 7,500 and 8,000 feet: the R. argenteum is a small tree, at 8,000 and 9,000 feet,strangely associated with Balanophora, Convallaria, Paris, Spheropteris, Laurus, and Magnolia. It was on the ascent of Tonglo, a mountain on the Nepalese frontier, that I beheld the Rhododendrons in all their magnificence and luxuriance. At 7,000 feet, where the woods were still dense and subtropical, mingling with Ferns, Pothos, Peppers, and Figs, the ground was strewed with the large lily-like flowers of R. Dalhousiae, dropping from the epiphytal plants on the enormous Oaks overhead, and mixed with the egg-like flowers of a new Magnoliaceous tree, which fall before expanding and diffuse a powerful aromatic odour, more strong, but far less sweet, than that of the Rhododendron. So conspicuous were these two blossoms, that my rude guides called out, "Here are lilies and eggs, Sir, growing out of the ground! "- No bad comparison. Passing the region of Tree-Ferns, Wallnut, and Chestnut, yet still in that of the Alder, Birch, large-leaved Oak (whose leaves are often eighteen inches long), we enter that of the broad-spathed Arum (which raises a crested head like that of the Cobra de capel), the Kadsura, Stauntonia, Convallaria, and many Rosaceae.The paths here are much steeper, carried along narrow ridges or over broken masses of rock, which are scaled by the aid of interwoven roots of trees. On these rocks grow Hymenophylla, a few Orchideae, Begonia, Cyrtandraceae, Aroideae of curious forms, the anomalous genus Streptolirion of Edgeworth, and various Cryptogamiae, and the Rhododendron arboreum is first met with, its branches often loaded with pendulous mosses and lichens, especially Usnea and Borrera. Along the flat ridges, towards the top, the Yew appears with scattered trees of Rhododendron argenteum, succeeded by R. Campbelliae. At the very summit, the majority of the wood consists of this last species, amongst which and next in abundance occurs the R. barbatum, with here and there, especially on the eastern slopes, R. Falconeri.
Mingled with these are Pyri, Pruni, Maples, Barberries, and Azaleas, Olea, Ilex, Limonia, Hydrangea, several Caprifoliaceae, Gaultheria, and Andromeda; the Apple and the Rose are most abundant. Stauntonia, with its glorious racemes of purple flowers, creeps over all; so do Kadsura and Ochna; whilst a Currant, with erect racemes, grows epiphytally on Rhododendron and on Pyrus. The habits of the species of Rhododendron differ considerably, and, confined as I was to one favourable spot by a deluge of rain, I had ample time to observe four of them. R. Campbelliae, the only one in full flower early in May, is the most prevalent, the ropes of my tent spanning an area between three of them. Some were a mass of scarlet blossom, displaying a sylvan scene of the most gorgeous description. Mr. Nightingale's (1) Rhododendron groves, I thought, may surpass these in form and luxuriance of foliage, or in outline of individual specimens; but for splendour of colour those of the Himalaya can only be compared with the Butea frondosa of the plains. Many of their trunks spread from the centre thirty or forty feet every way, and together form a hemispherical mass, often forty yards across and from twenty to fifty feet in height! The stems and branches of these aged trees, gnarled and rugged, the bark dark-coloured and clothed with
(1) At Embley near Romsey, Hants, the seat of William Edward Nightingale, Esq., whose beautiful grounds boast of drives through what may really be called woods or groves of Rhododendrons, many of them self-sown. -- The mention of these grounds (adorned with exotic Rhododendrons) by a naturalist luxuriating amidst the aboriginal species of the lofty mountains of Sikkim-Himalaya, makes me desirous to introduce here a brief notice of the plants in question. I could not trust my own memory for a correct statement of what it has been my privilege to see, but Miss Nightingale has obligingly communicated to me the following particulars:--
"Our Rhododendrons were chiefly planted about thirty years ago: the largest number are in an exceedingly wet 'bottom' of deep black peat full of drains, sheltered with sloping banks of Birch and Fir, with a good deal of Laurel, large Kalmias and Azaleas near the road. This part was originally a nursery-garden of about four acres: the shrubs have been cut continually to keep the road clear, and now make a bank seventeen or eighteen feet high. They are scattered over the high ground (a dry black sand) for about two miles, where they cover another bank of heathery soil and another bottom of the deep peat. There are not above a dozen of the R. maximum amongst them, and about three times as many of the arboreum and hybrid Scarlets which we find quite hardy, but which seem to flower best in the high and dry situations. The Ponticum and var. roseum seed themselves to a great extent, and the consequence is an immense variety in the shape, size, and colour of the flowers, hardly any two plants being quite alike.
"The largest single Rhododendron is one hundred and fifty feet round and twenty feet high: there are several of ninety-seven and ninety-eight feet round, but these have been cramped for room by their neighbours. The tallest I can find grows between a Birch and a Portugal Laurel, and is twenty-five feet high, its single upright stem measuring nineteen inches in circumference. It is quite an exception, for they fork generally immediately on emerging from the groumd; and though there is one which measures five feet ten inches in the girth of its trunk an inch from the ground, yet as he leaves his good ways and divides immediately after, I am not sure you will grant him his diploma as a tree. The forks are from eighteen inches to two feet in circumference. The variegated kind, with long footstalks to the flowers, has perhaps the thickest stem with us. The outside branches of the large individuals root themselves all round and make impenetrable thickets. We plant out the seedlings, which come up very thickly wherever an open space gives them room, and they are now scattered over most of the wild ground about. I think this is pretty nearly all we have to tell, but we may add that the Kalmias and Yellow Aaleas are some of them ten feet high and wide in proportion."
It may be interesting to record some particulars of another favoured spot for Rhododendrons, namely, Penllergare, Glamorgan, the seat of Dillwyn Llewellyn, Esq., who writes in reply to my queries:--
"The soil and climate of this district suit that class of plants well, as is attested by the seedlings of the common Rhododendron Ponticum,which appear in thousands throughout our woods. The rough sketch I enclose is of this species: it measures in height fifteen feet ten inches, and completely covers a circumference of one hundred and ten feet. The plant grows by itself upon a lawn, without any trees to overshadow or interfere with it, and it forms a perfectly symmetrical and compact shrub, with dense foliage and short-jointed wood. We have also a specimen of R. aboreum, var. roseum, nine feet four inches in height, and in circumference forty-eight feet: it was planted fifteen years ago and has never received the slightest protection. Like the last, it stands alone on a lawn, and is of a beautifully compact form. It has 3,200 flower-buds now upon it. The single stem from which it rises measures one foot nine inches in girth. The American species also flourish here with great vigour. A specimen of R. Catawbiense measures nine feet six inches in height, and covers forty-one feet six inches of circumference: this, however, is much younger than either of the preceding. It is also growing under the shade of large oak-trees, for which reason it is somewhat drawn and not so fine and thick in its growth as it might otherwisehave been."
It may be observed that Mr. London, in his Arboretum Britauicui, has not described any specimens of Rhododendron arboreum of the size above given. The largest he has noticed are at Wimbledon House, thirty-three feet in the spread of its branches; at Cufnells in Hampshire, thirty-nine feet ditto; Woburn Abbey, twenty-eight feet ditto; Shipley Hall, Derbyshire, fifty-six feet ditto, and sixteen feet the greatest height. ED.
spongy moss, often bend down and touch the ground: the foliage, moreover, is scanty, dark green, and far from graceful; so that notwithstanding the gorgeous colouring of the blossoms, the trees when out of flower, like the Fuchias of Cape Horn, are the gloomy denizens of a most gloomy region. R. Campbelliae and R. barbatum I observed to fringe a little swampy tarn on the summit of the mountain,--a peculiarly chilly-looking, small lake, bordered with Sphagnum, and half-choked with Carices and other sedges: the atmosphere was loaded with mist, and the place seems as if it would be aguish if it could, but was checked by the cold climate. R. barbatum had almost passed its flowering season: it is a less abundant and smaller tree than the last mentioned, but more beautiful in the brighter green and denser foliage, clean, papery, light-coloured bark, the whole forming a more picturesque mass.Along the north-east and exposed ridges only, grew the R. Falconeri, in foliage incomparably the finest. It throws out one or two trunks, clean and smooth, thirty feet or so high, sparingly branched: the branches terminated by the immense leaves, deep green above, edged with yellow, and rusty red-brown below. The flowers are smaller, but more numerous in each head than in the two last mentioned (R. Campbelliae and R. barbatum).The temperature of the earth in which the above species grew, was, in the middle of May, at twenty-seven inches below the surface where the roots are chiefly developed, 49º 5' at all hours of the day: that of the air varied from 50º to 60º. In naming the new species before me of this eminently Himalayan genus, I have wished to record the services of some of those gentlemen who, besides Mr. Griffith (to whom a species had been already dedicated by Dr. Wight), have most deeply studied the vegetable productions of the country: they are Drs. Wallich, Royle, and Falconer. With their names that of Dr. Campbell, the Political Resident at Darjeeling, author of various excellent Essays on the Agriculture, Arts, Products, and People, &c., of Nepal and Sikkim, is no less appropriately associated; and in compliment to his amiable Lady I designate that Rhododendron which is most characteristic of Darjeeling vegetation; while to the Lady of the present Governor-General of India, I have, as a mark of grateful esteem and respect, dedicated the noblest species of the whole race. J. D. H.