1923] WILSON, THE HORTENSIAS 233 



THE HORTENSIAS 

 HYDRANGEA MACROPHYLLA DC. AND HYDRANGEA 



SERRATA DC. 



Ernest H. Wilson 



The flower-loving peoples of China and Japan have cultivated in their 

 gardens from time immemorial a number of plants beautiful for their 

 flowers, foliage, or habit of growth. In the early intercourse of western 

 nations with the Orient it was these that were carried to Europe and many 

 of them have become the most familiar and most prized of our garden 

 plants. The origin of many of these plants is still obscure, though in recent 

 years several have been discovered growing wild in the interior parts of 

 China and Japan. During the twenty years which I have devoted largely 

 to the investigation of the flora of eastern Asia I have taken much interest 

 in the problem of these long-cultivated plants. It has been my good 

 fortune to elucidate the origin of a number including the China Monthly 

 Rose, the Tea Rose, several Azaleas, the Chinese Pear, Apple, Cherry 

 and others including the subject of this note. 



There is no more familiar plant in the gardens and greenhouses of this 

 country and of Europe than the so-called Hortensias. These Hydrangeas 

 have been long cultivated in the West and in the hands of the plant- 

 breeders, principally those of France, have given rise to a wonderfully 

 varied group of valuable decorative plants. It was Thunberg, in 1784, 

 who gave the first binominal names to these Hydrangeas but he referred 

 them wrongly to the genus Viburnum. Other botanists at later dates 

 have given them other names. To clear up the synonymy it was necessary 

 to know exactly what the plants were that Thunberg named in his Flora 

 Japonica. In order to accomplish this I wrote to Professor H. O. Juel 

 at Upsala who most courteously had made a set of fine photographic 

 prints of Thunberg's specimens. The material in Thunberg's herbarium 

 consists of these seven specimens: 



Viburnum macrophyllum a. = Hydrangea macrophylla DC. 



Viburnum macrophyllum &. = Hydrangea macrophylla DC. 



Viburnum serratum <*. = Hydrangea serrata var. stellata Wils. 



c _ 



Viburnum serratum &. = Hydrangea macrophylla DC. 



Viburnum serratum T. = Hydrangea serrata DC. 



Viburnum serratum 5. = Hydrangea serrata DC. 



Viburnum serratum e. = Hydrangea serrata DC. 

 The first-named, Viburnum macrophyllum, is the familiar Hydrangea 

 with fleshy, shining green leaves and globose heads of pink, blue or white 

 sterile flowers, variously known as H. vpuloides K. Koch, H. hortensis 

 Smith, H. Hortensia Sieb. and so forth. The second. Viburnum serratum, 

 is the- Hydrangea with dull green thinner leaves and more slender shoots 

 which is hardier than the former. Of this, too, there are many garden 

 forms cultivated. 



