Year	Events	Reference
1753	The Paeonia genus was described for the first time and named one species Paeonia officinalis L., with two varieties, feminea and mascula	[9]
1794	The first tree peony plant was introduced and called Paeonia suffruticosa, from Guangzhou, China	[10]
1818	The first monograph on Paeonia was published, which included 13 species divided into two major species groups,fruticosa and herbaceae	[11]
1829	The first Paeonia species of the New World (North America) was recorded and named Paeonia brownii	[12]
1890	The Paeonia genus was reclassified into three subgenera, Moutan, Onaepia, and Paeonia	[13]
1943	The genus divided into three major groups: sect. Moutan, including all woody peonies; sect. Onaepia, including all herbaceous peonies in the New World; and sect. Paeon (=Paeonia), including all herbaceous peonies in the old World	[3]
1963	The intersectional hybrid peonies, so called Itoh hybrids, were bred using pollen of tree peony P. suffruticosa “Alice Harding” on the white, semi-double herbaceous peony “Kakoden”	[14]
1988	The chromosomal numbers of Paeonia spp. were calculated	[15]
1991	Propose to classify species and cultivars according to their morphological characteristics, flavone/flavanol patterns in the petals	[16]
1997	Propose to classify species and cultivars according to DNA analysis	[17]

Table 1: The history of Paeonia spp. identification and classification

	*P. muscala*	*P. tomentosa*	*P. wittmanniana*	*P. wendlboi*	*P. archibaldii*
Inflore- scence	solitary and terminal	solitary and terminal	solitary and terminal	solitary and terminal	solitary and terminal
Sepals	- Elliptic	- Oblong and obtuse	- Orbicular or ovate orbicular	- Broad	- Orbicular
	- Pale green to purplish	- Pale green	- Green but with purple peripheryor entirely purple	- Pale green	- Brownish green with red innervation and a wide reddish purple margin
	- Hairy or	- Hairy on the outside		- More or less hairy on outer side
	glabrous on the outside
Petals	- Elliptic	- Elliptic	- Elliptic	- Elliptic to broadly ovate	- Elliptic
Petals	- Pink, red, or white	- White	- Pale Yellow to white	- Pure yellow	- Pure white
Stamen	- Purple filament	- Yellow or violet filament	- Yellowish white purple filament	- Yellow filament	- White filaments and staining pinkish at the base
Stamen	- Anthers are approximately 4.5 mm long	- Anthers are approximately 4.5 mm long	- Anthers are approximately 4.5 mm long	- Anthers are approximately 4.5 mm long	- Anthers are approximately 4.5 mm long
Carpels	- 2 carpels	- 3-5 carpels	- 1-5 carpels	- 3-4 carpels	- Glabrous
	- Densely hairy	- Densely hairy and very rarely are glabrous	- Glabrous	- Densely hairy carpels

Stems	- 40-70 cm height	- 20-50 cm height	- 50-70 cm height	- 20-40 cm height	- Dwarf plant
	- Glabrous	- Simple stems	- Simple stems	- Simple stems	- Glabrous
	- Simple stems			- Brownish violet to purple.	- Simple stems
	- Oblong and purple				- Green, but at the base with s ome reddish staining
Leaves	- Lower leaves biternate	- Lower leaves biternate	- Lower leaves biternate	- Lower leaves biternate	- At first purplish red gradually be dark green at end of vegetation
	- Upper leaves smaller and simple ternate	- Upper leaves smaller,simply ternate or pinnate	- Upper leaves smaller, simply ternate or pinnate	- Upper leaves smaller and simply ternate	- Lower leaves biternate
	- Hairy in lower surface of leaves	- Ovate to elliptic shapes	- Broad—obovate, oblong	- More or less hairy only on the lowersurface of leafs	- Distinctly glabrous throughout

Refere- nces	[32]	[32]	[35]	[32]	[31]

Table 3: Some morphological traits of Paeonia genus characterized in Iran

species	Locations	References
P. mascula	Quercus forest, in Kurdistan province	[32]
P. tomentosa	Drazno Mountain and Golestan forest, in Golestan province	[32]
	Sangdeh forest, Chamestan, Siah Bisheh, Kelardasht and Ramsar, in Mazandaran province
	Manjil, Damash, Chaboksar and rodsar, in Gilan province
	Asalem to Khalkhal Road, in Ardabil province
P. wittmanniana	For identification, there has been a debate between plant taxonomists	[26]
P. wendelboi	Khlkhal, Ardabil province	[32]
P. archibaldii	Firouzkoh, Mazandaran province	[31]

Tables at a glance

Figures at a glance