In the original description of the characters of the genus _Hydrangea_ by Linnæus, there is no mention made of two different kinds of florets, as in the _Viburnum_, nor has any author that I am acquainted with described the _Hydrangea arbor._ as producing such; yet, to my great surprise, in a plant of this sort which flowered in my garden at Brompton in July 1797, three of the Cymæ, and three only, threw out each of them from their circumference a very different flower from those in the centre, smaller indeed, but very similar to the flowers of the _Hydrang. hort._ see Pl. 437. In 1788, Mr. Walter published his _Fl. Carolin._ in which he describes a second species of _Hydrangea_, which he calls _radiata_,[2] having very distinctly, as in the _Viburnum_, two different kinds of florets in the same Cyma, this variation in the florets is added by him to the generic character: the similarity which exists between the flowers of Mr. Walter's _Hydrangea radiata_, and those of the present plant sufficiently justify Dr. Smith in making it an _Hydrangea_; the appearances observed by Loureiro[3] on dissecting the germen, and our discovery of the existence of two different kinds of flowers in the _Hydrangea arborescens_, tend still more to confirm its propriety; we may add, that in the very habit of these several plants there exists a considerable similarity; still, however, it is only by ripe seed-vessels of the present plant, that this doubtful matter can be satisfactorily cleared up; but it will not follow, that if it be not an _Hydrangea_ it must be a _Viburnum_. This magnificent and highly ornamental plant, according to Dr. Smith, was introduced from China to the royal garden at Kew, by Sir Joseph Banks, Bart. in 1790; it was imported by Mr. Slater about the same time, with whom it is said to have first flowered in this country.