(2010)  Page(s) 162-167.  
 
In Caryologia (2010) 63(2), from the abstract:
Genus Rosa (Rosaceae) has a base chromosome number of x = 7. Ploidy levels of wild species range from 2n=2x=14 to 2n=8x=56. In this paper, one decaploid, the highest naturally occurring ploidy ever reported in the genus, was detected in the karyological study of an endemic wild species, R. praelucens Byhouwer to Zhongdian Plateau, Yunnan, China.... According to its karyomorphology, R. praelucens derived not from auto polyploidization directly but from inter-specific hybridization. Polyploidization associated with the effect of high altitude environment and inter-species hybridization both might have played important roles in the origin of R. praelucens.
at p.162 ff:
R. praelucens Byhouwer, first nominated by BYHOUWER (1929), was collected from Zhongdian Plateau, Yunnan, China by Forrest in 1914. It has ... the following characters: styles free and short, stipules adnate and not laciniate, flowers solitary, receptaculum armed and depressed-globose (BYHOUWER 1929). Owing to its large and showy flower with diameter to 15 cm and pink flower color when full blooming, it arose much interest of horticulturist...
Zhongdian Plateau lies in the south-eastern edge of Himalaya range, with an average altitude of 3400 m. 14 species of the genus Rosa were recorded in this area... The plants were grafted from buds of wild R. praelucens plants, which were located at an altitude of 3231m [10,600 ft]...Shoot tips were collected from the plants showing vigorous growth....measurements of chromosome arms were taken from at least ten well-spread metaphases of five shoot tips....The metaphase separation ... of R. praelucens clearly showed that it had 70 chromosomes.