This is a very familar name, whether styled as a species (P. suffruticosa), or as a nothospecies implying hybrid origin (P. × suffruticosa). It appears to us to exist nowadays as little more than a variably defined taxonomic dumping ground for shrubby hybrids, which we have chosen to treat in other ways. Hence, we do not use the epithet but briefly outline the various ways it has been used.
It is important to understand that this is a Western concept applied to East Asian plants, some of which were already well understood in other ways in Asia, some of which were not. The name P. suffruticosa was first applied by Andrews in 1804 to a double, pink-flowered Central Plains cultivar (Bean 1976). Hence, whatever else is grouped here, the name must cover such plants if it is used at all. As further Central Plains and Japanese cultivars were brought to the West, they were also placed here. From the late 19th century, plant collecting in China by Europeans and Americans brought other woody peonies to attention. Among these were descriptions of what we would now call wild P. rockii by Reginald Farrer (McLewin & Chen 2006), specimens and seed collected by William Purdom in Shaanxi which have since been attributed to P. jishanensis (q.v.), and seed of Gansu cultivars sent by Joseph Rock; all these were placed under P. suffruticosa by Stern (1946). Over 40 years later, Haw & Lauener (1990) still felt able to use it in this broad way, accepting three subspecies, with subsp. suffruticosa to cover at least the Central Plains varieties, subsp. rockii apparently covering both P. rockii and Gansu cultivars, and subsp. spontanea more or less equating to P. jishanensis.
Thorough investigation of the wild ancestors of the various Chinese hybrid cultivars has been relatively recent, and mostly the work of Chinese botanists, culminating in Hong’s (2010, 2011) monograph. Even with the acceptance of P. rockii, earlier publications retained the name P. suffruticosa for some wild forms (Hong & Pan 1999). Later ones abandon it altogether, with the acceptance of P. jishanensis and P. cathayana (Hong 2010).
This leaves P. × suffruticosa available for Central Plains and potentially some other hybrid cultivars. This is still common in contemporary Western garden literature. Edwards & Marshall (2019) for example use it for at least Central Plains and Japanese, but not Gansu cultivars. It seems to be used more sporadically in the Chinese research literature. The standard works on Chinese cultivars (Wang 1998; Li 2005) do not use it in their systems; the former mentions it only among synonyms of wild ancestors while the latter lets this dangerously convenient term slip in undefined at least once (p. 18). It is still quite often encountered, undefined, in non-taxonomic research literature, for example by Lv et al. (2020) who use it for a Central Plains cultivar.
Our aim here (see introductory article on Paeonia) is to present the plants in an informative way, not to create a formal, watertight framework for classifying hybrids within the taxonomic hierarchy – surely a thankless task – and we have no compuction in avoiding this unhelpful name.