It is gratifying to learn from your last number that the grand display of Rhododendrons brought out by Mr. Anthony Waterer has been so satisfactory, and attracted, as it ought, so much attention at the Centennial Exposition. It will, no doubt, bring this comparatively little known native shrub, with its superb varieties, into more prominent notice, and accelerate its more general introduction into our gardens. Certainly it must show how safely they can be transplanted when it is recollected that the plants, some of them quite large, were out of the ground at least three weeks, and yet produced a magnificent display of flowers.

Your remark that "not one in a hundred of the thousands of visitors has ever seen one before," reminds me of the article on the Rhododendron in Appleton's Encyclopedia (first edition). Who prepared it I do not know; but its value or correctness may be estimated when it is stated "that in the Northern United States the great Rosebay (R. maximum), will alone endure the winters." As this was written before Alaska was purchased, I do not know what Northern States are intended; for the R. Cataw-biense and its varieties are the only kinds that are generally grown in the gardens of Massachusetts; R. maximum, although a native, being far less common than the former. For forty years in our grounds they have not suffered from the winters, and have Outgrown in the same time the maximum. If the writer had seen or even heard of Mr. Hunnewell's 'fine collection at Wellesley, he must have known the Catawbiense endures our winters as well as the maximum.

Such authority is, of course, not of any importance to intelligent cultivators; but to those unacquainted with the plants, it helps to retard their introduction into our grounds. In fact, beyond a mere enumeration of the species, from Loudon's Arboretum,, more information can be obtained from any nurseryman's catalogue. After nearly half a century of experiments in hybridization, the grand results of which you have given in your notices, and the details of many of which have been published, it would seem that an instructive and very valuable paper might be prepared, showing the gradual progress made in the improvement of this truly regal shrub. It would be a great incentive and encouragement to follow up this advancement, at the same time adapting them to our more severe climate.

It is really astounding to find that the Rhododendron, Azalea and Kalmia are so little known. At least one-half of the many hundreds of visitors who have come to look at our collection, just going out of bloom, did not know "which was which;" the Azaleas and Rhododendrons being in bloom at the same time, and the Kal-mias also, for about a week before the former were gone. Our reply was that the shrubs with the large evergreen-looking foliage were the Rhododendrons, and the small-leaved ones the4 Azaleas, or sometimes that those with the yellow, orange, salmon, buff or scarlet flowers were the Azaleas; and quite a number made the remark that the Kalmias looked a great deal like the Laurels that grow wild in some parts of the State!

The predominating "sap," as you term it, of the R. ponticum and arboreum, in most of the splendid varieties so far produced, precludes their cultivation in our climate north of Washington, and it illustrates the fallacy of what is termed "acclimatization," for with the intermixture even of the " sap " of arboreum in the fourth and fifth generations, the tender character of the Asiatic species still continues to crop out, and although the plants rarely die, their foliage is disfigured, and the flower buds partially or wholly destroyed by our severe winters. Unfortunately this is not generally known. The English and Belgian catalogues describe them as hardy, as they are in their climate, and the brilliancy of the colors as compared with Cataiobiense is so charmingly beautiful that a choice selection is made accordingly. The plants are imported, and planted out with all due care, but at the end of two or three years nothing is left but the stock upon which these superb kinds are grafted.

Twenty-five years ago, when the late Mr. Standish first began the hybridization of Rhododendrons, and raised that beautiful variety, Minnie, with others which were said to be very hardy, I imported ten of the best seedlings, two plants of each, but up to this time they have never produced a single flower, and only two or three are alive; these grow up every year a foot or two high, and are killed down again by the winter; and just ten years ago (18G6) we imported one hundred of the hardy varieties from Belgium, including Lord Clyde, Minnie, Baron Osy, Mooresenum, and other fine sorts. The first year, while small, they were wintered by placing a frame over them, filling in with dry leaves, and covered with sashes. They kept well and flowered, but soon grew too tall to be covered. "We then planted them out, to give them a trial, in our Rhododendron bed: now we have not even one left.

In time I don't doubt we shall obtain very dark-colored Rhododendrons perfectly hardy, but all the experiments so far show how difficult is the work. The Indian blood which carries color also carries with it a perfect bar to hardihood of white, blush, pink, rose, rosy lilac, rosy purple, and rosy crimson. We have as fine hardy sorts as can be desired; but of fancy colors, and deep red and crimson colors, we have none. It is to the production of the latter that the efforts of our hybridizers should be directed.

Forty years' experience in the cultivation and production of Rhododendrons and Azaleas has enabled us to learn something of their character. Under the right treatment no plants grow more freely, none transplant more safely, few require less care, and none give so grand a display of blossoms. Many of our specimens, now forty years old, have been transplanted but once; one twelve feet high and twelve broad, and producing every year thousands of flowers. Some seasons the bloom is more abundant than others, but out of an acre of Rhododendrons, Azaleas and Kalmias we have never known a plant to be seriously injured. This year the snap of bloom has been simply magnificent.

I regret that I could not find the time to visit the Centennial, and see the great display of Mr. Waterer, as well as those of the Messrs. Parsons. It was no little labor to bring 1500 plants across the Atlantic, and the thanks of all lovers of beautiful shrubs are due to him for his commendable efforts to place before the American people these superb varieties, the parents of which cover the mountain regions not many miles from Philadelphia.

Mr. S. B. Parsons, in your September issue, in his article on Centennial Rhododendrons, while criticising the plants exhibited by Mr. Waterer under the tent, as being too tender for this climate, concludes by saying: " There are Rhododendrons, however, which are perfectly hardy in our American climate, and doubtless Mr. Waterer has them. These high colors are not, however, found among them, but belong to sorts which are adapted only to greenhouse culture."

Surely Mr. Parsons must have forgotten that the finest collections in this country, Mr. Hunne-well's, at Wellesley and Mr. Rand's, at Dedham, besides many others around Boston, such as Mr. Sargent's, at Brookline - all came from Mr. Waterer. Some of these collections consist of several thousand plants in many varieties, all doing under the heavy mulch treatment of eight to ten inches of dead or decaying leaves, quite as well as the same plants do in England.

I have for many years grown the annexed list, with only the slight protection in winter of evergreen branches on the northwest side, and though many of my plants suffered from the severe winter and summer droughts of 1872-73, yet I am not aware they have ever suffered from cold many degrees below zero.

Among the varieties I have grown here with success are the following, imported from Mr. Waterer many years ago:

Everestianum,

Mrs. Milner,

Mrs. McClutton,

Blandyanum,

Album Grandiflorum,

Album elegans,

Roseum Grandiflorum,

Old Port,

Andersonii,

Towardii,

Scipio,

Caractams,

Catawbiense Album,

Charles Bagley,

Purpurexim elegans,

Lady Armstrong,

Atrosanguineum,

Onslowanum,

Delicatissium,

John Waterer,

Titian,

Minnie,

Purity,

Stella,

Mrs. Halford,

Mr. Hunnewell, certainly the. best grower of Rhododendrons in this country, writes me to-day on the subject:

"I do not think the difficulty arises from the cold, but from the drought, which is undoubtedly the case with most evergreen failures. If you will give Rhododendrons a good depth of soil in the first place, say at least eighteen inches of one-third peat or leaf soil, one-third sand and one-third the top soil of an old pasture well-rotted and in a place where they do not get the mid-day sun, and mulch very thoroughly - twelve to twenty inches - of well-rotted leaves. The earth under them is always moist and cool in our hottest weather."

Of course, if one had great facilities for watering Rhododendrons there would be less necessity for heavy mulching. This, however, has another advantage, - the annual decay of the lower leaves of the mulch forms an admirable pabulum or food for the plants.

Mr. Nelson's idea in your September number, that the roots of overhanging trees do no harm to Rhododendrons is a great mistake, for if nothing else they absorb the moisture and food, which, did they not exist, would go into the Rhododendrons. A wood or mass of trees on the south side of Rhododendrons is very well, but the roots of this wood should be always kept out of the Rhododendron bed by annual cutting back.

I presume Mr. Nelson is praising our native Rhododendrons having but one color, and could he but see the collection at Wellesley of perhaps fifty or more colors from "Old Port," almost black, to "Purity," nearly white, and every intervening shade, he would be astonished. There are many better evergreens than the American Yew.