Rhododendron maximum. - The generic name is derived from the Greek, rhodon, a rose, and dendron, a tree, because the flowers resemble, in color, bunches of roses. In the Northern States, it is a straggling shrub, of very irregular growth, but one of the most magnificent in foliage and flower the country can boast of. It is abundant in the Middle States, and in the mountainous tracts of the Southern, but in New England rare. It is found near Portland, Leicester, and in a swamp in Medfield, in this state.

The Rhododendron is generally under ten feet in height in this part of the country, but sometimes attains the height of twenty or twenty-five feet in a less rigorous climate. The places where it is found, in New England, may be considered as beyond its proper natural limits, and it will be met with only in warm swamps, under the shelter of evergreens, and where the roots are protected by water, which usually overflows these places.

The flower-buds are often destroyed, even thus situated, in very severe seasons. When the leaves are beginning to unfold themselves they are rose-colored, and covered with red down. When fully expanded, they are smooth, five or six inches long, of an elongated oval form, and of a thick coriaceous texture. They are evergreen, and partially renewed once in three or four years. It puts forth flowers in June and July, which are, commonly, rose-colored, with yellow or orange dots on the inside, and sometimes pure white, or shaded with lake. They are always collected at the extremity of the branches, in beautiful groups, which derive additional lustre from the foliage that surrounds them. Previous to its expansion, the whole bud forms one large compound bud, resembling a strobilus or cone, each individual one being covered by a rhomboidal bracte, which falls off when the flower expands. The corolla is mo-nopetalous, (one piece or petal,) funnel-shaped, with a short tube, the border divided into five large, unequal segments. There is but a small chance of plants succeeding which have been taken from swamps. The surest way to propagate it is by seed, from which it readily grows, but requires time and patience to bring it into a flowering- state.

Shade and humidity seem almost indispensable to the growth of this shrub. Deeply shaded situations, where the atmosphere is laden with vapors, are most congenial to its growth. It is, therefore, well calculated for the shrubbery. With a little attention, it may be inured to stand the sun, and then forms a stately ornament for the lawn or grass-plot. The proper soil is a light, rich, peaty loam, with moisture. It will grow, however, in almost any, and flourish on a strong, heavy loam. It may be propagated from cuttings and layers, from young, healthy branches of ripened wood, and, managed as ordinary plants, thus increased. There are many exotic species, which are beautiful, and highly ornamental to the green-house. R. ponticum and many others will withstand the winter in the open ground, if well protected, as most of them are natives of cold, mountainous regions, and covered in the winter by Alpine snows.

R. maximum is one of the parents from which a numerous family of splendid varieties have been produced, all equally hardy, and are only to be known, and their cultivation understood, to make them more common. The Messrs. Hoveys have exhibited, at the Horticultural Rooms, the flowers of many splendid varieties, grown in their nurseries, at Cambridge, in the open ground, fully exposed to the sun, in a rather low, moist location, and a peaty soil.