Shrub to 2.5 m tall, differing from P. decomposita in the following ways: carpels usually 3 rather than 5; disc enveloping carpels nearly to the base of style at anthesis, rather than only half way; leaf segments fewer, 19–39 rather than 29–65; terminal leaflets rhomboid to orbicular rather than elliptic to orbicular. (Hong et al. 2001; Hong 2010, 2011)
Distribution China NW Sichuan, SE Gansu
Habitat Sparse Cupressus chengiana forests, young secondary deciduous forests, thickets; 2000-3100 m.
USDA Hardiness Zone 5-9
RHS Hardiness Rating H6
Conservation status Not evaluated (NE)
Delicately divided leaves and purple-pink, single flowers make this a beautiful peony (Gießler Päonien Kulturen 2020). P. rotundiloba exists as a few wild populations in the Minjiang Valley of NW Sichuan and in Tewo County, SE Gansu, where it is isolated from P. decomposita by the 4,000 m high Qionglai Range (Hong 2010; Hong 2011). It was recognised as a distinct species as recently as 2011 (Hong 2011), so mentions of P. decomposita in the literature and in gardens must be treated with caution. It is in cultivation at low levels in Europe, and has been offered commercially (initially as P. decomposita) by the Gießler nursery, Germany, where it flowers in early to mid-May (Gießler Päonien Kulturen 2020). Zhou et al. (2014) found no molecular evidence that P. rotundiloba was one of the progenitors of hybrid woody peonies in China.