Article (magazine)  (2001)  Page(s) 251.  
 
In a recent article in The New Plantsman (Haw (2001)), I accepted the conclusions of D. Y. Hong, Pan and Yu (1998), that the Paeonia delavayi complex (i.e. Paeonia L. subgenus Moutan (DC.) Seringe Section Delavayanae (F C. Stern) J. J. Halda) could be divided into only two species. P. delavayi Franch. and P. ludlowii (Stern & Taylor) D. Y. Hong. This makes good taxonomic sense, but clearly causes some problems for gardeners, as plants that are quite distinct for horticultural purposes are now all merged into the single species, P. delavayi..... I now propose to resolve at least most of these problems by dividing this one species into two varieties and several formas. It must he borne in mind, however, that intermediates between these varieties and formas certainly exist in the wild, so that distinctions between them are not by any means entirely clear-cut.

Article (magazine)  (2001)  
 
Paeonia delavayi Franch., Bull. Bot. Soc. Fr. 33: 382 (1886)...
KEY TO VARIETIES
1. Shrub more than 1 m tall (usually up to c. 1.8 m):...... 1. var. delavayi
1. Shrub or subshrub up to not more than 1 m tall:..... 2. var. angustiloba

1. var. delavayi
KEY TO FORMAS
1. Petals entirely red or dark red to purplish-red, or sometimes red with yellow margins:.... 1a. var. delavayi f. delavayi
.....Included in this forma are all taller-growing variants of the species with predominantly red flowers in this type forma: P. delavayi of gardens, with dark red flowers belongs here.

Article (magazine)  (2001)  
 
Many gardeners and some botanists may find it surprising that all taxa formerly recognised in Subsection Delavayanae have been reduced to synonymy with P. delavayi Franch., except for P. lutea Delavay var. ludlowii Stern & Taylor, which has been raised to specific rank. Good reasons have, however, been put forward for these changes. D. Y. Hong, Pan and Yu (1998) analyse several populations of P. delavayi sensu lato and show that it is impossible to discern clear distinctions between them. D. Y. Hong (1997) makes a convincing case for raising P. ludlowii to the rank of species. These conclusions are supported by RAPI analysis, as reported by Y R Zou, Cai and Wang (1999).

Article (magazine)  (2001)  
 
KEY TO SPECIES
1. Flowers usually 2 or 3, more or less pendent; disc fleshy, surrounding only the base of the carpels (Section Delavayanae (F. C. Stern) J. J. Halda): 6
6. Carpels usually 2-5, sometimes more; petals, filaments and stigma often not entirely yellow; plants usually less than 2 m tall: .....6. P. delavayi

6. Paeonia delavayi Franch. in Bull. Bot. Soc. Fr. 33: 382 (1886); Huth, Bot. Jahrb. 14: 273 (1892);.....Shrub or subshrub,....glabrous throughout. Roots often fusiformly thickened, widely suckering. Lowermost 2-3 leaves biternate, the leaflets divided into 3-11 primary segments, these in turn each more or less deeply cleft into 2-11 lobes; segments and lobes linear to narrowly lanceolate, entire or occasionally dentate. Flowers 1 or 2-3 (3) on each shoot, 4- 10 cm diam.; petals yellow, yellow with a red or purplish basal blotch, red or purplish-red, or sometimes white, orange, greenish-yellow, or yellow with a red margin. Disc green, yellowish, yellow, red to dark red. Carpels 2-4(-8). W China (west & south-west Sichuan, W Yunnan, SE Tibet).
Many gardeners, and perhaps some botanists, will find it hard to accept that the several formerly recognised species and varieties listed as synonyms above should now all be included in the single species P. delavayi, with no infraspecific taxa. There are, however, good reasons for this, which have been carefully researched and explained by D. Y. Hong, Pan and Yu (1998). They have shown that characters that have previously been used to separate taxa now all included within this species, such as flower colour, presence or absence of a conspicuous involucre and width of leaf segments, are all very variable and show little or no correlation with each other and with geographic distribution.

Book  (Jan 2000)  Page(s) 49-50.  
 
Stern's second subsection of tree peonies, subsection Delavayanae, includes several species discovered in the mountains of Southwestern China toward the end of the 19th century. In it, he identified and defined the following species:
Paeonia delavayi Franchet
Found in North Yunnan in the Lijang range. This relatively bare-stemmed shrub can reach a height of up to 5.5 feet. The leaflets appear in clusters of three; those at the end of the stem stand clear of the rest. The hidden flowers are smaller than those of the suffruticosa group, with characteristic blackish red or maroon petals, the darkest in the genus. The thick, fleshy lobes, which form the disc at the base of the carpels, are another distinguishing feature. Though the species has no genuine garden merit, it is the source of the dark maroon colors in today's tree peony hybrids. Plants raised from collected seed routinely differ somewhat in habit of growth, shade of color (some are quite attractive reds), and size. Hardy to U.S. Department of Agriculture hardiness zone 5, though it seldom blooms in climates colder than zones 7 or 8. Diploid (10 chromosomes).

Book  (Jan 1999)  Page(s) 632.  
 
Paeonia delavayi Tree. Species... among the most common and easiest of tree peonies to cultivate... Chinese species... bright to very deep black-red flowers

Book  (Jan 1999)  Page(s) 18, 19, 21.  Includes photo(s).
 
Page 18: Photographed at Highdown, Sussex.
Page 19: Paeonia delavayi found in pine forests in the Lijiang mountain range in North Yunnan province... discovered by the French missionary Père Jean Marie Delavay in 1884.

Book  (1999)  Page(s) 137.  
 
Paeonia delavayi, West China, 1949

Article (magazine)  (Jan 1955)  Page(s) 12.  
 
P. delavayi....vera - Introduced 1930 by Lemoine. Said to have come from China but whether from a wild source or a garden is not stated. Lemoine says differs from the type in habit, quickly attaining five feet. Also differs in foliage. Flowers large, single, darkest mahogany crimson.

Article (magazine)  (Jan 1955)  Page(s) 12.  
 
Paeonia delavayi Franchet, Bull. Soc. Bot., France, 1886.
Collected by Pere Delavay in 1884 in Yunnan and named for him - flowered and first exhibited in Paris, 1892, although other reports say first introduced 1900. It was collected again by Forrest in 1910. This is believed to be the oldest and most primitive species of this group. Seedling forms differ, one being reported to six feet. Flowers dark mahogany which give it the common name, the maroon tree peony, although it is also commonly called the Delavay tree peony. Its flowers are three and a half to fo ur inches. The flowers have conspicuous involucres of eight to twelve green bracts inserted close against the prominent calyx of five leathery, greenish sepals. This species is distinguished from P. lutea and P. potanini by this conspicuous involucre with the greater number of bracts and sepals.