Paeonia lactiflora

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Paeonia lactiflora⁽¹⁾

Herbs perennial. Roots thick, cylindrical or carrot—shaped, attenuate toward tip, up to 30 cm long, 2 cm in  diameter. Stems up to 1 m tall, glabrous, very occasionally hispid. Lower leaves biternate; terminal leaflets  often 2- or 3—segmented; leaflets/leaf segments 10-15, rarely 9 in number, lanceolate or ovate-lanceolate,  cuneate or decurrent at the base, acute at the apex, 4.5—16 cm long, 1.5—6 cm wide, usually with bristles along  veins or sometimes glabrous above, glabrous or sparsely pubescent along veins beneath; margins white  cartilaginous-thickened, dentate—spinose on the thickenings. Flowers usually 3—4 on a stem, both terminal and  axillary, sometimes only the terminal one developed with 2—3 axillary sterile buds, very rarely solitary without  sterile flower buds, single (in wild populations) or double (in cultivated plants), 8—13 cm across; involucrate  bracts 4 or 5 in number, unequal, leaf-like; sepals 3 or 4 in number, broadly ovate or suborbicular, 1—2 cm  long, 1-1.7 cm wide, all caudate at the apex; petals 9-13 in number, white or pink (in wild populations), or  various in colour (among cultivated plants), obovate, 3.5—6 cm long, 1.5—4.5 cm wide; filaments yellow;  anthers yellow; disk yellow or red, 1—5 mm high, waved or incised; carpels 2-5 in number, green, red or  purple, glabrous or rarely sparsely hispid or tomentose, with hairs 1-1.5 mm long; stigmas sessile, red, 1.5—2.5  mm wide. Follicles ovoid or oblong-ellipsoidal, 2.5-3 cm long, 1.2-1.5 cm in diameter. Seeds black, ovoid-  spherical, 7 mm long, 6 mm in diameter.

Chromosome number: 2n=10

Growing in bushes and grasslands, but also in open woods, at altitudes  from lowlands to 2,300 m, but to 3,400 m in Sichuan Province (Kangding), China. In E Asia:  China, the Korea Peninsula, E Mongolia, and Russia (the Far East and SE Siberia).

The most distinct character of Paeonia lactiflora is the cartilaginous thickening along the leaf  margins, which are dentate—spinose on these thickenings. Historically, the crossing experiment  conducted by Saunders and Stebbins (1938) demonstrated that this species was incompatible with P.  anomala, P. Veitchii, P. emodi, and four other species, and thus seemed in a very isolated position.  However, our unpublished molecular data (CPAT, Adh1 and Adh2) imply that the species is closely  related to P. emodi. In the subsection Albiflorae, P. emodi and P. lactiflora have fewer leaflets/ leaf segments.

Petals and carpels in Paeonia lactiflora are rather variable in colour in wild populations. The  former were found varying from pure white, whitish pink to pink, whereas the latter varied  from green, pink, red, purple to dark purple even within a single population. We  found both glabrous and pubescent carpels within populations, and therefore  P. albiflora var. trichocarpa Bunge is here treated as synonymous to P. lactiflora.

This species is widely cultivated for both ornamental and medicinal purposes. Flowers are  always doubled in cultivated varieties of Paeonia lactiflora.