(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.

(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.

(2001)  
 
Paeonia delavayi Franch....
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
2. var. angustiloba Rehder & Wilson in Sarg., Pl. Wilson. 1: 318 (1913)...

KEY TO FORMAS
2. Petals white:.... 2c. var. angustiloba f. alba

2c. var. angustiloba f. alba (Bean) S. G. Haw, stat. nov. Typus: t. 49 in Stern, Stud. Gen. Paeonia (1946) (holotype). Syn. P. delavayi var. alba Bean, Trees and Shrubs 3:265 (1933); P. potaninii f. alba (Bean) Stern, Stud. Gen. Paeonia 49 (1946).
This name is applied to white-flowered, low-growing plants of the species, which Sir Frederick Stern (1946: 49) called P. potaninii f. alba.

(2001)  
 
Paeonia delavayi Franch....
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
2. var. angustiloba Rehder & Wilson in Sarg., Pl. Wilson. 1: 318 (1913)...

KEY TO FORMAS
1. Petals red or dark red to purplish-red:...... 2a. var. angustiloba f. angustiloba
This name includes the typical 'P. potaninii', a low-growing plant with deep maroon-red flowers.

(2001)  
 
Paeonia delavayi Franch....
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
2. var. angustiloba Rehder & Wilson in Sarg., Pl. Wilson. 1: 318 (1913)...

KEY TO FORMAS
2. Petals orange or yellow:...... 2b. var. angustiloba f. trollioides

2b. var. angustiloba f. trollioides (Stapf ex Stern) S. G. Haw, stat. nov. Typus: China, NW Yunnan, Deqen, Baima (= Beima) Shan, Mekong-Yangtse divide, 11,000 ft., open stony pastures, Forrest 13195 (holotype, E). Syn. P. trollioides Stapf ex Stern, Journ. Roy. Hort. Soc. 56: 77 (1931); P. potaninii var. trollioides (Stapf ex Stern) Stern, Stud. Gen. Paeonia 50 (1946); P. X franchetii J. J. Halda, Acta Mus. Richnov., Sect. Nat. 4 (2): 31 (1997).
I include plants with orange flowers under this name, but, as noted under var. delavayi f. lutea.... these may be the result of hybridisation between plants with red and yellow flowers, so this inclusion is more or less arbitrary.

(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

2. var. angustiloba Rehder & Wilson in Sarg., Pl. Wilson. 1: 318 (1913). Typus: China, W Sichuan, W of Tachien-lu [Kangding], descent to Yalung River [nr. Yajiang], 3000 - 3600 m, Oct. 1908, Wilson 1333 (holotype A - n.v.). Syn. P. potaninii Komarov, Not. Syst. Herb. Hort. Petrop. 2: 7 (1921).
Here belong all the low-growing plants (Ed. In the wild the normal tall clump-forming plants of P. delavayi var. delavayi are in marked contrast to the low-growing var. angustiloba. Whereas the former produces tight clumps and only occasionally suckers, the latter is often widely suckering and, on occasions, no more than 30 cm tall in flower.) of this species, attaining not more than 1 m in height. Previously they have often been regarded as a separate species, (e.g. by Stern (1946: 49-50)). The flower colour varies from dark purplish-red through yellow to white and I accordingly recognise three formas on the basis of this colour variation. The name var. angustiloba has priority in this rank, having first been published in 1913.

KEY TO FORMAS
1. Petals red or dark red to purplish-red:...... 2a. var. angustiloba f. angustiloba
1. Petals orange, yellow or white: 2
2. Petals orange or yellow:.......... 2b. var. angustiloba f. trollioides
2. Petals white:.......... 2c. var. angustiloba f. alba

(2001)  
 
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 orange or yellow to greenish-yellow, or yellow blotched with dark red at the base, or yellow with a red margin:..... 1b. var. delavayi f. lutea

1b. var. delavayi f. lutea (Delavay ex. Franch.) S. G. Haw, stat. nov. Typus: China, NW Yunnan, Eryuan County, Mt Hea Chan Men, 25 May 1883, Delavay s.n. (lectotype, P - n.v., isolectotype, K); Syn. P. lutea Delavay ex Franch., Bull. Soc. Bot. Fr. 33: 382 (1886)....Included here are all the taller-growing variants of the species with predominantly yellow or orange flowers. Orange-flowered plants may be the result of hybridisation between plants with yellow and red flowers and their inclusion here is therefore more or less arbitrary. P. delavayi var. lutea of gardens belongs here. As far as I can ascertain, there is no clear record of white-flowered plants tall enough to be placed with this variety.