Magazine  (2013)  Page(s) 30. No. 46..  
 
Charles Quest-Ritson. Rosa x hardii - Lost and Found.
In the Autumn 2012 edition of our Journal, I mourned the loss to cultivation of Rosa x hardii.....

This is excellent news indeed. We now hope that a nurseryman may be persuaded to propagate.....

Book  (2012)  Page(s) 67.  
 
Rosa berberifolia Monophylla à une feuille...
Rosa berberifolia hardii, nouvelle variété.

Book  (Nov 1994)  Page(s) 121-122.  
 
xHulthemosa hardii (Rosa hardii) presumed to be a cross between Hulthemia persica and Rosa clinophylla...It appeared in the Jardins de Luxembourg, Paris, in 1836, probably from seed of Rosa persica. The fact that it has remained in cultivation for so long cannot be attributed to its vigour as we know it, for it is notoriously difficult and short-lived, though more tractable than Hultemia persica...it attained 9 feet by 9 feet, against a wall...

Book  (Apr 1993)  Page(s) 253.  
 
x H. hardii (Cels) Rowley (Rosa x hardii Cels); Hulthemia persica x Rosa clinophylla; Hardy before 1836... striking 2 in. yellow flowers with the crimson eye of Hulthemia...

Book  (1993)  Page(s) 124.  
 
The Rose Garden, Royal Botanic Gardens, Melbourne.
Introduction. The Rose Garden, situated near "C" gate contains a collection of rose species, as well as hybrids of historical importance....
Rockery. This rockery contains a number of sprawling, more or less prostrate roses. R. 'Max Graf' is a useful rockery plant. R. x hardii has yellow flowers with an unusual central blotch. It is an interesting hybrid involving Hulthemia persica, a close relative of the roses from Iran.

Book  (1993)  Page(s) 64.  Includes photo(s).
 
[Listed under "Wild Roses and Their Cultivars"] An early Rosa persica hybrid. Requires more heat and warmth than most roses. Raised in the Luxembourg Gardens, Paris by its director, Alexandre Hardy, in c. 1786; Rosa clinophylla was said to be the seed parent. Summer flowering. Susceptible to mildew. Height: 6 ft. Some scent.

Book  (1988)  Page(s) 18.  Includes photo(s).

Book  (1985)  Page(s) 157.  
 
Only one hybrid between R. persica and another rose had ever been known. It was raised in the Luxembourg Gardens in 1836, and was called 'Hardii'. It also has yellow flowers, paler but larger than those of R. persica, and it exhibits a fine red eye. Alec [Cocker] had about fifty plants of 'Hardii'... He determined to raise a new race of roses from it, but after a few years he discovered that 'Hardii' was incapable of setting seed, infertile in pollen, utterly sterile. The answer, he decided, was to forget 'Hardii', and obtain the species which had borne it, R. persica.

Book  (1981)  Page(s) 247, 250.  
 
R. x hardii Cels = R. clinophylla x R. persica
Similar to persica but much taller. Flower light yellow with a red blotch at the base of each petal.

Book  (1981)  Page(s) 125.  
 
R. x hardii Cels Flowers two inches across, yellow petals with an orange spot at the base of each. Hardy made several crosses of R. persica and other roses. Hardii was the only one distributed to nurseries and was described by Cel Frères with a colored plate in 1835.