Book  (2010)  Page(s) 243.  
 
Hybrid nothospecies...Paeonia lemoinei Rehder, J. Arnold Arb. 1: 194 (1920)...Paeonia lemoinei is an intersubsectional hybrid between P. delavayi (subsect. Delavayanae) with yellow flowers and P. suffruticosa subsect. Vaginatae. The cross was first made by the French nursery company Lemoine et fils in about 1900. This hybrid is only known to exist in cultivation.

Article (magazine)  (2001)  
 
Intersectional hybrid taxon
Paeonia x lemoinei Rehder, Journ. Arnold Arb. 1: 194 (1920). Typus: plate in Gard. Chron., ser. 3, 57: supplementary plate (1915)....P. saundersi Haworth-Booth, The Moutan or Tree Peony: 30 (1963), nomen nudum. This hybrid is only known to exist in cultivation. The cross between P. delavayi (with yellow flowers: 'P. lutea') and P. suffruticosa was first made by the French nursery company Lemoine et fils in about 1900. There are now several named cultivars of this hybrid, the oldest being 'L'Esperance' and 'La Lorraine'. The name must also apply to all crosses between any plant belonging to P. delavayi sensu lato, irrespective of flower colour, and P. x suffruticosa. When Rehder named the hybrid, he did not designate any acceptable holotype, saying only that 'The form 'L'Esperance' may serve as the type of this hybrid though he provided no reference to any specimen or illustration of this cultivar. He did, however, cite references to two illustrations of 'La Lorraine'. The best and most easily available of the illustrations cited is the colour plate designated as lectotype above. This hybrid has frequently been overlooked by taxonomists of tree peonies.

Article (magazine)  (Jan 1955)  Page(s) 14.  
 
Paeonia lemoinei Rehder 1920. P. lutea X suffruticosa Lemoine about 1900 or Henry before then.
The hybrid group is apparently now used to include all the Henry, Lemoine, and Saunders hybrid varieties, but under botanical rules this could hold only if P. lutea is considered as a botanical variety of P. delavayi and not as a distinct species. The species P. delavayi probably enters into the parentage of most or all the darker hybrid varieties.