The Horticultural Department is hardly yet in a condition to do justice to the exhibitors, and a critical notice must be deferred till the future. In the meantime the following sketch intended for the mass of the people not well versed in Horticultural matters, from Forney's Daily Press of May 11th, giving an account of appearances at the opening, may serve as an introduction to more solid matter which will probably follow: how horticutural hall looked.

Thomas Meehan's Description - Features of the Exhibition already in Place.

The rain, so dampening to the well-wishers of the great opening, provoked so monotonous a series of remarks all around that I was glad to meet the cheery face of Mr. John Stevenson, the landscape gardener of the Centennial Grounds, for surely, thought I, here is one who will like to be congratulated on the timely rain, and so we ventured on that strain. But no! It was all right, he thought, for bringing out the bright green grass and the shiny foliage of the deciduous trees, but of what use was that if the people could not enjoy it? The trees and vegetation, both those natural to the beautiful grounds as well as those furnished by the exhibitors, seemed really to enjoy the timely gift from heaven, and I entered fully into their thankful spirit. But there are few natural flowers as yet. The dogwood, which the wits tell us is known by its bark, as well as by its beautiful white flowers, was ready for the occasion; and the red bud, which is the American representative of that tree which, according to the Book of Gerard the Herbalist, and which in the "ancient writings " of the Horticulturist, is "ye tree whereon Judas did verilye hang himself," was covered with its rosy blossoms. The weather, after all came out just right.

English weather in the morning - American in the afternoon, just fair and right for an international exhibition.

The Horticultural Grounds are not yet quite completed by the exhibitors, but so far as the work is done it is a marvellous success. In the exhibitions of the Old World the plants were removed just as ordinary nursery trees are-with the usual result - a deplorable appearance the whole summer after. But our American exhibitors have improved on this. Many of them have had their trees growing in tubs and pots for a whole year ahead, and now that they are set out, they are leafing out and blooming as if they were "to the manor" as well as to the "manner" born. There is little doubt the outdoor Horticultural Department of the Centennial Exhibition will be the most successful of that class ever held in the world. Most of the exhibitors have their plants plainly and tastefully labelled, thus making the collections to the highest degree educational. It was said in an English horticultural periodical that some of the English nurserymen intended to come over with their goods and astonish the Yankees. It is astonishing that their plants have arrived in such good condition, but it seems just likely that the astonishment will be mutual, and do good all round.

It was pleasant to meet on the grounds so many representatives of foreign firms: Benary, of Errfurt; Court, of the celebrated firm of the Veitches; Waterer, the rhododendron man; and Williams, famous for the introduction of new tropical plants, were on the grounds. Waterer, with his rhododendrons, was first on here. They are not displayed yet, but if superior to those of the American firm of Parsons & Son, of Flushing, they will be very fine indeed. The leading exhibitors, who have in a measure completed their plantations, are S. B. Parsons & Sons, R. B. Parsons & Co., of New York; Asher Hance & Sons, of Red Bank, N. J.; Hoopes Bros. & Thomas, of West Chester; Veitch & Sons, of Chelsea, England; and in azaleas, Waterer, of London; Robert Buist, of Philadelphia; Miller & Hayes, of Mount Airy; Verdier, of Paris; and Ch. Pohl, of Austria. The last has a collection that will astonish Americans by its novelty. It is a collection of gooseberries and currants grafted, on the stem of our wild Missouri currant, which is a strong sort, growing four or five feet high.

These are already in front of Horticultural Hall, in flower, and when the red fruit matures they must make very striking objects.

The Japanese have a small collection of dwarf evergreens in front of their building. The kinds, however, have for the most part been already introduced by our enterprising nurserymen, and are found in their collections. It shows that the celebrated skill of the Japanese in dwarfing evergreens is fully matched by our own horticulturists. They simply select the dwarf forms - the Tom Thumbs of the vegetable kingdom - and propagate from them. The trained fruit trees of some of the European exhibitors are greater monuments of skill.

Horticultural Hall is yet but partly filled. Plants cannot travel long distances in cold weather, and the more tender kinds must yet wait a while. It is wonderful that so much is already here. Mr. B. S. Williams, of Holloway, near London, has been very successful in bringing over a nice lot of rare hot-house plants. These are in the northeast conservatory. The plants are, of course, small in comparison with what our home florists can contribute, but it is a remarkable collection for so great a distance. The several varieties of Bornean pitcher plants attract much attention from the curious visitor. In this house there is a small but very choice collection of those tropical curiosities, known as orchids or air plants. Many more are expected later in the season, when the weather is safer for their transportation. These few are from Mr. Sturtevant, of Bordentown, N. J. Among these flowers are mimic representatives of the ornithological and entomological worlds. S. B. Parsons & Sons, of Flushing, N. Y., have a collection of ferns in this division, which is pronounced exceedingly choice by those skilled in pteridology.

The centre of the house is occupied by Australian tree ferns, contributed by Miller & Sievers, of San Francisco. In the northwest house we found Mr. Taplin, the well-known superintendent of Geo. Such's fine collection at Amboy, N. J., with what is so far the most valuable collection of tropical plants in the Exhibition. There is a plant of the snowy wax palm, some twelve feet high, of which small specimens are valued at $100 each. Usually, palms have a graceful look, but the devil palm, Daemonorops hystrix, is horrible to look upon. The usually humble fern gives us here a representative with a stem five feet high. This is the way they grow in Australia. There are plenty of sago palms in the hall, but here is one in flower. It looks as if nature had simply placed a crown of oak leaves on the head of the palm. The flowers, however, come to nothing, as among sago palms marriage is necessary to perfect happiness. A new kind of sago palm is in Mr. Such's collection, called Cycas circinalis. The sago is made from rotting the stems - expensive sago at the figures at which these plants are held. The whole collection of palms is perhaps one of the most valuable ever seen at any great exposition, and surprises those of our English friends who fancied Americans far behind in these tasteful luxuries.

The flamingo plant drew numbers within its brilliant circles. It is somewhat allied to our well-known calla lily, but few but botanists would suspect the relationship. There are about fifty expanded flowers on it. The florists call it Anthurium Scherzerianum. Not fit to associate with respectable vegetation, and therefore, confined in a small glass case, is a collection of those savage little things known as insectivorous plants. They have cut loose from the simple habits of their forefathers, Mr. Darwin tells us, and have taken to eating bugs and flies, not refusing pieces of beefsteak when they get a chance. There is one kind from New Holland, another from Java, and one wretched little fellow was found in our own country, near Wilmington, North Carolina. They are all here safely guarded by the box, and in imprisonment together. And those oddities, the cacti, have some choice representatives in this superb collection. The visnaga, or Mexican tooth-pick cactus, is among them. This one is only about the size of an ordinary football, though it would hardly do as a substitute, but in its own country it grows to the size of a sentry-box, and the writer has helped to handle one that weighed over a ton. Nature must have been in a strange mood when she made these things.

Just beside these is the table-formed house-leek, looking for all the world like a cabbage rolled out flat. Perhaps Nature, tired of the labor involved in cactus-making, sat on these plants to rest, and thus these flattened results. Across the hall, in the southeast conservatory, is the Cuban contribution of Mr. Lachaume, of Havana. The good old gentleman was personally attending to the placing of his pets, many of which have suffered severely from the long voyage to a cooler clime. Very appropriate to the Centennial occasion is his collection of century plants, embracing over forty kinds. In one corner he has several blocks of plants cut from the forest giving a better idea of these tropical wood-growths than all one could read about them in a lifetime. Here are orchids and cactuses and ferns, and " preacher in the pulpits " of a decisively tropical countenance, all seemingly as happy together as a bunch of soup-herbs in our Eastern Market-house. Among the curious plants in this collection are numerous forms of the "Dutchman's pipe-vine." The American forms are shabby fellows in comparison with these. They throw out a long lip-like petal. veined precisely like a piece of flesh, but the mimicry does not stop here.

The plant has become too lazy to work, and seems to have studied out a plan to make insects slave for it. Instead of fertilizing itself it depends on insects for carrying the fertilizing pollen to the pistil, and in order to lure them to this thankless task, besides the flesh trick above referred to, it creates a stench to which that which the fiend introduced about the good Saint Anthony was incense itself. The insects are enraptured with the prospective carrion, rush in, and in this way fertilize the flower, but find, alas! when too late, that they have entered their tomb, and in a few days wholly disappear in the form of food for the large ants that have their home in great abundance in these parts of the world. Capital texts for sermons, these Centennial experiences afford, but these matters I shall leave to our clerical friends.

But we must not linger long in any one place to-day. The Hall itself, under the direction of Chief Miller, is quite as forward as any other department; but new attractions will now appear every day. In a hurried look we noted the great sago palm owned by Robert Morris, which has a stem now, perhaps, four feet high; and there is another remarkably beautiful one from Mr. De Puy, of Cuba, with the leaves so regular and close that it is the envy of those having a passion for these things. There is a small plant of the sacred fig of the Hindoos which will catch many an eye when it gets a label on. Several plants are here of the now famous Eucalyptus globulus, a competitor in growth with Jonah's gourd; with the "brave old oak " of England in the solidity of its timber; with Jayne's, Helm-bold's, and all other antidotes combined as a febrifuge; and with everything under the sun - so a French professor tells us - for securing sleep to one's mother-in-law, soundly in spite of dulcet sounds from mosquitorial pipes. There are also Acacias in great numbers, but too late in the season to see them " wave their yellow hair; " a fine camphor tree, some twenty feet high, and a great number of kinds of banana plants.

A large plant marked "Chocolate tree," is unfortunately not that celebrated plant; but there are guavas, Japan plums, mangoes, Indian rubbers, and many similar things which we often read about but seldom see. Many visitors missed the side rooms, but there are nice things to see from Peter Henderson, H. A. Dreer, Francoise Huss, who has some remarkably well-arranged skeleton leaves; Charles H. Marot, with a set of beautifully-bound volumes of the Gardener's Monthly, in a beautiful case to match, and Hewes & Co., of Boston, Mass., have some remarkably beautiful specimens of horticultural pottery ware. For Waterer's Rhododendrons, a house to be covered by a muslin shade has been started, in which the plants are to be arranged as in a tasteful piece of landscape gardening, Only for the immense conservatory near it, the Rhododendron house would be thought a mammoth structure.