86 JOURNAL OF THE ARNOLD ARBORETUM [vol. v 



at higher elevations than other Hupeh Rhododendrons and next to them 

 in this respect comes R. adenopodum Franch. No small-leaved Rhododen- 

 dron of the class which covers so many hundreds of square miles of the 

 Chino-Thibetan borderland has been discovered in western Hupeh or 

 eastern Szechuan, neither can Rhododendrons be termed a dominant 

 feature of the vegetation in these parts of China. They are, however, a 

 fairly common and strikingly beautiful element of the flora. 



Of the eighteen species nine are not known to grow elsewhere though 

 one (R. hypoglaucum Hemsl.) is very closely related to a species indigenous 

 in western Szechuan, and another (R. Houlstonii Hemsl. & Wils.) is very 

 close of kin to R. Fortunei Lindl. of eastern China. R. Augustinii Hemsl. 

 grows also in western Szechuan where it is rather rare and so, too, does 

 R. pittosporaefolium Hemsl. which has also been found in Hunan province. 

 Quite recently R. Wilsonae Hemsl. & Wils. has been found on the moun- 

 tains of northern Kwangtung. Of the remaining six species, three (R. 

 ovatum Planch., R. Mariesii Hemsl. & Wils. and R. molle G. Don) have 

 their headquarters in eastern China and their western limits of distribution 

 in Hupeh. One (R. micranthum Turcz.) is a wide-spread species in north 

 China, Manchuria and Korea which has its southern limits in Hupeh; 

 another (R. yanthinum Bur. & Franch.) is a western species with its eastern 

 limits in Hupeh. The remaining species (R. Simsii Planch.) is universally 

 distributed through all the warm temperate parts of China. 



The first of the endemic species was discovered about 1886 by A. 

 Henry who altogether brought five new species to our knowledge though 

 one was not recognized until 1910. Pere P. Farges in the neighborhood 

 of Tchen-keou-ting discovered between 1891 and 1894 six new species. 



onae Hemsl. & Wils. to the list. One species (R. 

 Augustinii Hemsl.) was first introduced into cultivation by Pere P. Farges 

 who sent seeds to M. Maurice de Vilmorin in 1899. With the exception of 

 R. detersile Franch. all the other species of the region were introduced into 

 cultivation (twelve for the first time) by myself during 1900, 1901 and 1907 

 through seeds sent to Messrs. Veitch and to the Arnold Arboretum; also 

 the stock of R. Augustinii Hemsl. in British and American gardens is from 

 seeds collected by me. All the introduced species have flowered in Britain 

 where they have proved as hardy as the rank and file of evergreen Rhodo- 

 dendrons, but in the Arnold Arboretum only one (R. micranthum Turcz.) 

 will grow out-of-doors. Though comparatively few in number these 

 Hupeh species are an important unit; several are in the front rank of the 

 genus. The blue-flowered form of R. Augustinii Hemsl. is one of the most 

 remarkable of Rhododendron and R. auriculatum Hemsl. is unique as the 

 last of its race to open its flowers in summer. Late-flowering and beautiful 

 is R. discolor Franch. and R. Fargesii Franch. is of its class one of the loveli- 

 est. 



KEY TO THE SUBGENERA 



Shrubs or trees with persistent, rarely deciduous, glabrous, lepidote or tomentose 

 leaves; stamens 5-20; ovary glabrous, lepidote or tomentose, never setose, 



Wil 



