See Paeonia Hybrid Cultivars including P. delavayi.
This name was coined by Alfred Rehder (Rehder 1920) at a time when it was conventional to give latinized binomials to novel classes of garden hybrids. He applied it to P. lutea × P. suffruticose, taking Lemoine’s hybrid ‘L’Espérance’ as the type. We do not find this a helpful category. Firstly, P. lutea is now regarded as merely a colour form, f. lutea, of P. delavayi; rather similar hybrids have been made using other colour forms. Secondly, P. suffruticosa is a confusing, unhelpful term that has been used in many ways to include various distinct classes of hybrid as well as some wild forms, which now carry other names, as discussed under P. × suffruticosa; the second parent of ‘L’Espérance’ appears to have been a Central Plains cultivar or an early European derivative thereof (Cheng 2007). Finally, breeding in North America has gone far beyond these early F1 hybrids to give an important assemblage of cultivars which cannot be contained within the concept of a nothospecies.