(1977)  Page(s) 310-327.  
 
Rehder (1940) provides the following criteria to distinguish between R. hugonis and R. xanthina:
R. hugonis: Bristles on main shoot present, 5-13 leaflets per leaf, leaflets oval, obovate or elliptical, 5cm flowers
R. xanthina: Bristles on main shoot absent, 7-13 leaflets per leaf, leaflets oval, suborbicular, rarely elliptical, 4cm flowers
Herbarium specimens of the two species were virtually indistinguishable: they were usually represented by lateral branches, so the character of 'main shoots with or without bristles' could not be used. Most flowers were imperfectly preserved....The two species could not be distinguished on number and shape of leaflets alone, as the overlap considerably....
...R. hugonis and R. xanthina do not deserve separate status as species and it is proposed to unite them retaining the former at the lowest rank of forma, viz.
Rosa xanthina Lindley form xanthina
Rosa xanthina Lindley forma hugonis (Hemsl.) Roberts