(1996)  
 
Paeonia decomposita was described in 1939 by Handel-Mazzetti on the basis of the specimen H. Smith 4641 from Chosodjo, N.W. Sichuan, China. Stern (1946: 142) considered it conspecific with P. suffruticosa Andr....Examination of the holotype of Paeonia decomposita shows that, contrary to Stem's (1946) opinion, it differs specifically from P. suffruticosa, including Rock's specimen (P. rockii). It is easily distinguished from both P. suffruticosa and P. rockii by its leaves that are compound 3-4 times, with (29) 33-63 leaflets; its rose petals, a white disc, and glabrous carpels, as shown in the following key.

1. Carpels glabrous; petals rose; disc white; leaflets (29) 33-63, glabrous on both surfaces ...... P. decomposita
1. Carpels tomentose; petals white, with or without a dark-purple blotch at the base; disc yellowish white or purple; leaflets 9 or 19-29, hairy along the veins underneath ... 2
2. Petals entirely white; disc purple; leaflets 9 ................. P. suffruticosa
2. Petals with a dark-purple blotch at the base; disc yellowish white; leaflets 19-29 ... P. rockii

To our knowledge, the wild form of Paeonia suffruticosa is confined to S.W. Shanxi Province and Shaanxi Province, and P. rockii only occurs in S.E. Gansu, S. Shaanxi, W. Henan and W. Hubei. Neither species is found in Sichuan Province. Fang's P. szechuanica is conspecific with P. decomposita and the former name should be treated as a synonym of the latter.

Deciduous shrub 50-150 cm, glabrous throughout; branches terete; bark grey-black. flakily peeling off; young shoots purple-red, with persistent scales at the base. Leaves alternate, usually the second from below best developed and with most leaflets, ranging from (29) 33 to 63, mostly three or rarely four times compound, the first and third division triple, the second pinnate; petiole 3.5-8 cm; lamina deltoid-ovate in outline, 15-22 cm x 10-20 cm, dark green above, pale green below; terminal leaflets elliptic or ovate, 2.5-6.5 cm x 1.2-3 cm, 3-partite to the base or 3-fid, the terminal segments 3-lobed, lobes elliptic, narrowly elliptic or ovate-lanceolate, 0.8-5.3 cm x 0.3-1.5 cm, pedolules 1-1.5 cm; lateral leaflets elliptic, 1.8-4.4 cm x 0.6-2.5 cm, 3-lobed or coarsely toothed, petiolules 0.1-0.5 cm. Rowers terminal, 10-15 cm in diameter. Bracts 2-3(-5), unequal in size, linear-lanceolate. Sepals 3(-5), broadly obovate, mucronate at the tip, green, 2.5 cm x 1.5-2.0 cm. Petals 9-12, rose, obovate, usually 2-lobed and irregularly incised or toothed at the apex, 4 - 7 cm x 3 - 5 cm. Disc white, papery, enveloping 1/2-2/3 of the carpels, with triangular teeth. Carpels mostly 5, very rarely 4 or 6, glabrous; style short, stigma flattened, recurved. Follicles green-brown when young, black-brown when mature, ellipsoidal, 2-3 cm, with. 1-3 seeds. Mature seeds back, shiny, spheroidal or broadly ellipsoidal, 8-10 mm long, 6-8 mm in diameter. 2n = 10 (Hong & al., 1988). Found so far only in a small area in N.W. Sichuan Province, China (31°15' to 31°54'N; 101°42' to 102°12'E), growing in loose thickets of spiny shrubs at altitudes of 2300-3100 m. Flowering from late April to early June. Not so far introduced into cultivation.