"Rhododendrons, the pride of European gardens, as they are of their native wilds" - so wrote the great Loudon nearly fifty years ago, when very few species or varieties were either known or cultivated in Europe; and even many of these, though deeply interesting and worthy of careful cultivation, by no means conspicuous or striking as decorative plants. The gorgeous Indian R. Arboreum was but recently introduced, and had not yet bloomed in this country, though wondrous things were said of its tree-habit and dark-crimson blossoms; and as yet the still popular R. Ponticum, Catawbiense, Caucasicum, maximum, ferrugineum, and hirsutum, and a few of their varieties, very nearly made up the list of what we may term showy sorts, though all were worthy of the high praise which was accorded to them.

Since then, it is scarcely necessary to say, a vast and in some respects a remarkable improvement has been effected, both in point of variety and quality, through the introduction of new species from their native habitat, as well as by the labours of hybridisers; so that, instead of the two or three sorts which were then so highly and deservedly appreciated, they can now be counted by the hundred, embracing among them every possible shade of colour from the faintest pink to the deepest crimson or scarlet, and from the purest white to the deepest purple, while the flowering season is protracted from February till the end of June - one variety following another without a pause during the whole period.

Rhododendrons are now more emphatically than ever the pride of European gardens, possessing as they do the most varied attractions to be found in any class of flowers, combined with the elegant habit and foliage of our finest evergreen shrubs, rendering them indispensable alike in the shrubbery, the flower-garden, or the conservatory - in each of these occupying a unique place, and never failing to elicit the highest admiration of all who have any appreciation of the symmetrical in form or the beautiful in colour.

This wonderful improvement has been effected chiefly through the crossing of the hardy late-flowering species with the early Indian sorts, particularly "Arboreum," itself too tender for open-air culture in this country; and it is to it that we are indebted for all the shades of scarlet, crimson, and pink, which are so much admired in our present race of hardy varieties. Among the first results of hybridising in this direction were the still well-known Russellianum and Alta-clarense from Catawbiense varieties, Smithii from Ponticum, and Noblicanum from Caucasicum - all possessing in a greater or less degree the fine crimson flowers of their male parent. It was soon found, however, that though sufficiently hardy to stand the winter outside in favourable situations, these hybrids inherited much of its tree - habit and early - blooming peculiarity; they were shy in forming buds, or rather they required many years before they attained sufficient size for blooming; while in nine cases out of ten the flowers were blighted by late spring frosts before they were fully expanded, detracting immensely from their value for outdoor cultivation, and rendering it necessary for their safety that they should be potted in autumn, and placed in the conservatory after they were done flowering; and while they were, as they still are, extremely useful for this purpose, seeing that they can be had in all their glory during the winter and early spring months, it was obvious that much was still required to be done before bright-coloured Rhododendrons could be got to flower in May and June. Hybridisers naturally turned to the late species and their varieties; and these were again crossed, but with the crimson hybrids; and this carried on with every possible combination, and through a series of generations, has gradually developed that infinite variety of habit, form, and shade of colour with which our collections are now so much enriched.

It would almost seem as if perfection itself had been attained; and a hybridiser may consider himself fortunate if, after having raised thousands of seedlings, he finds even one sufficiently distinct from, or even up to, the high standard of those already grown. The work, however, is still enthusiastically prosecuted, and from year to year novelties and improvements make their appearance.

The introduction within the last twenty-five years of these magnificent species from Sikkim, Assam, and Bhotan, with their wonderful diversity of foliage, form, and colour, along with, in some cases, exquisite fragrance, has opened up a new and inviting field for further efforts in hybridising. The most of these species, though hardy enough to survive our winters in the open air in sheltered situations, bloom too early to be useful in any other way than as conservatory plants; and the great object to be obtained is to infuse some of their peculiarities of foliage, colour, and above all, fragrance, into the late-flowering varieties. This has been hitherto a slow process, owing to the extreme difficulty of inducing many of them to intermix with the European and American species and hybrids. At the same time considerable progress has been made, and already a few fine hardy hybrids have been introduced; while a new race of valuable greenhouse varieties - the result of crossing among themselves - has been created, which are already high in popular favour.

In crossing Rhododendrons with a view to obtain hardy and late-flowering seedlings, we invariably choose the hardiest variety for the female parent, being satisfied from experience that the offspring inherit much more of the nature of the female than of the male in this respect; and when one of the sorts is tender, there is no species that we know of better adapted to form the basis of a hardy race than R. Catawbiense, which combines elegant foliage and showy flowers with an ability to bear any amount of frost that it can be subjected to in this country, along with a tendency to flower freely in a young state. It has been largely used by the most successful hybridisers, and its presence can easily be detected in some of our most useful and showy hardy hybrids.

R. maximum is also an excellent species for hybridising with the tender sorts, being hardy and late-flowering, and having fine compact trusses, the florets clear in colour and of a thick wavy texture, enabling them to resist hot sunny weather better than most sorts; but it has the drawback of being a shy bloomer, and is used with greatest advantage after being first crossed with some of the free-blooming sorts. Some of the finest varieties have been obtained from its hybrids.

When early-forcing sorts are the objects in view, by far the best is R. Caucasicum, itself so early as frequently to expand its blush-coloured flowers in mid-winter in the open air. It is dwarf in habit, and a most prolific bloomer; and it has produced many most admirable varieties for such a purpose, including Noblicanum and Nobli-canum album, first crosses by Arboreum and Cinnamomeum, both of which are invaluable for conservatory decoration from the middle of December till the end of February - a season when effective flowers are neither plenty nor varied.

Hugh Fraser.

(To be continued).

Leith Walk Nurseries, Edinburgh.