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4. Cultivar Classification

There are many cultivars of tree peonies and their morphological and biological characteristics are different. The differences also exist in the origin and the evolutional extent. In order to facilitate the scientific management, popularization and utilization, as well as satisfy the needs of new cultivar breeding and practical utilizing, cultivars should be classified. There are many classification methods. In these, the classification system which is mainly based on flower forms reflects best of the relationship of cultivar's origin and evolution. So it is the focus of the research. Other classification methods which have practical values should be used in the same time.

4.1 Advances of Research in Cultivar Classification

4.1.1 Cultivar Classification of Ancient Tree Peonies

The Simple History of Developing

As talked above, tree peony cultivars formed in or before the Tang Dynasty and thrived in the Bei Song Dynasty. Although there were few detailed records in the Tang Dynasty, people had still described some ornamental characters of tree peony. They had started distinguishing single, semi-double and double flower form which gave the evidences of that there were not only single also semi-double and double cultivars. In the same time, flower color had rich changes, too. In the Song Dynasty, Ou Y.X. described the cultivars in detail in Luo Yang Mu Dan Ji. Besides the origin, producing areas, main characters and the name reason, he already started to combine double extent with flower color in describing flower's main characters, such as "single, white flower", "semi-double, red flower", "double, purple flower" and so on. Lu Y. had clearly classified according to flower color in Tian Peng Mu Dan Pu. Until the Ming Dynasty, Wang X.J. introduced the classification method which combined flower color with flower form in Qun Fang Pu. The classification principles and methods which were used in ancient times still have practical values until now.

The Main Classification Methods

Classify Mainly by Flower Color Lu Y. of the Song Dynasty classified tree peony as red, purple, yellow, white and blue flowered cultivars according to flower color in Tian Peng Mu Dan Pu. Gao L. of the Ming Dynasty classified ancient Bozhou tree peony as yellow, bright-red, peach, pink, purple and white flowered cultivars in Zun Sheng Ba Jian - Mu Dan Hua Pu. In the Qing Dynasty, the anthography classified tree peony mainly according to flower color. Su Y.M. divided tree peonies into 9 color types - crimson, pretty-red, pink, simple white, silver-red, black purple, yellow, green and secondary color in Cao Nan Mu Dan Pu. Yu P.N. first divided tree peonies into two color types - pure color and secondary color in Cao Zhou Mu Dan Pu. In pure color type, yellow is the first, then blue, red, white, black in turn. In secondary color type, there are pink, purple and green. Zhao divided tree peonies into 8 color types in Xin Zeng Sang Li Yuan Mu Dan Pu. They are black, yellow, green, white, purple, red, pink and mixed color. Mixed color contains lotus-like pink, deep blue, pinkish blue etc. 'Er Qiao' had appeared in that time and was listed in red-flowered cultivars in Zhao Pu.

Classify First by Flower Color and then by Flower Form This method classified tree peonies mainly by flower color and took flower form as a complement. The representative was Wang X.J.' s classification system in Qun Fang Pu in the Ming Dynasty. First, tree peonies were divided into yellow, red, pink, white (contain light blue), purple and secondary color (contain black purple, brown, versi-color) flowered cultivars according to flower color. And then each color was further divided into single, semi-double, double-flat, double-crown flower form etc.

Classify According to Ornamental Characters As a representative, Xue F.X. divided tree peonies into 6 types -marvelous, famous, smart, elegant, capable, comprehensive -according to ornamental characters in Bo Zhou Mu Dan Shi. In fact, such classification method was used as early as the Song Dynasty. Wang G. divided the herbaceous peony into 7 grades: —better, less well in the first class; better, less well in the middle class; better, middle, less well in the lower class—in Yang Zhou Shao Yao Pu in the Song Dynasty. The classification method according to ornamental characters had practical values and was widely used in goods producing after the Ming Dynasty.

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4.1.2 Modern Cultivar Classification of Tree Peonies

Advance of Research

As the introducing areas expanding and breeding jobs under going, in China or even in the world, tree peony cultivars are increasing day by day and cultivar-groups which adapt to different habitats appeared. The classifying jobs become more and more important in accord with this. But because of the differences in cultivars' evolutional extent of different areas, so the classification methods are different on the cultivar classification system of tree peony.

The Cultivar Classification of Overseas Peony The cultivar classification of Japanese tree peony is very simple. K. Uehara divided them into only 4 forms. They were: single, petals 5-15, one layer; semi-double, petals 20-40; double, petals 45-100; super-double, petals over 100. Later, B. Miyazawa (1932) made some corrections referring to the herbaceous peony' s flower form, and set out 9 forms: single, golden-stamen, anemone, crown, bomb, semi-rose, rose, semi-double and flat-rose etc. In Japan, nowadays the flower form classification combining with flower color is still simple. Tree peonies are divided into red, purple, black, white, versi cultivars according to flower color.

There are 5 common forms in the classification of Euramerican peonies. They are single, Japanese, anemone, semi-double and double (Arno & Irene Nehrling 1960). In addition, some classification scheme divided them into 6 forms. They are single, Japanese, semi-double, bomb, crown and rose (Hottes, translated by Cui Y. W. 1946).

The classification of former Soviet Union is also simple. Such as Kucepew (1952) set out 3 forms: single, semi-double and double; Lebedow (1949) set out 5 forms: single, Japanese, anemone, semi-double and double. The head botanical garden of the academy of sciences of Soviet Union (1960) set out 7 flower forms in 3 types. They are: A, single type: single; B, semi-double type: (a) Japanese, (b) anemone, (c) semi-double; C, double type: (a) semi-globular, (b) crown, (c) rose.

The Peony Cultivar's Classification in China Since 1960, many flower form classification methods about peony cultivars were successively published. Here, some which has more effect were listed as follows:

Zhou Jiaqi 's Classification System (1962)

The contemporary Chinese tree peony research' s trailblazer, Zhou J.Q. of Beijing Forestry university published "The discussing of peony's flower form classification"in the magazine of Acta horticulturae sinica in 1962. He divided peony cultivars into 3 types 11 flower forms: A, single type: (1) single; B, double type: (2) lotus, (3) chrysanthemum, (4) rose, (5) hundred-proliferation; C, crown type: (6) golden-stamen, (7) anemone, (8) golden-circle, (9) crown, (10) globular, (11) crown-proliferation.

In this method, the cultivar evolutional relationship was first taken into consideration and then the flower form and the practical use were too. This is the basic views and main contributions of Zhou J.Q.'s classifying method. It has built up the basic pattern of flower form classification. The cultivar classifying principles and methods which were set up based on an academician of the Chinese academy of sciences, Chen J. Y.' s cultivar classification research in Prunus mume and Mr. Zhou J.Q.' s

classification research in peonies. They had been continually perfected by Chen J.Y. and were further accepted as Chinese flower cultivars dualistic classification system, and got vital effect in China and abroad.

Yu H. 's Classification System (1962)

Yu H., the contemporary grand old man of Chinese tree peony researcher, a professor of Shandong Agricultural University, thought the tree and the herbaceous peony should be classified alone. He (1962) suggested 3 types 9 flower forms. Later, he added several forms then set out 3 types 11 flower forms*: A, single type: (1) single; B, semi-double type: (2) lotus, (3) sunflower (such as ' Er qiao'); C, double type: (4) rose (such as ' Yipin Zhuyi'), (5) mudan (such as 'Lantian Yu'), (6) flat-globular (such as 'Yao Huang'), (7) round-globular (such as 'Lihua Xue'), (8) long-globular (such as ' Bai Yu'), (9) globular (such as ' Jia Gejinzi'), (10) flat-proliferation, (11) crown-proliferation. This method further divided double type into 3 subtypes: flat-head, crown and proliferation. This system was the overviews of tree peony classification made by Yu H. (1986), namely 3 types, 3 subtypes, 11 flower forms, 8 colors (yellow, white, pink, red, purple, black, green, blue) was classified first by flower form and then by flower color.

Qin K.J. and Li J.J. 's Classification System

Qin K.J. and Li J.J. published "The classification study of peony cultivars based on flower form"in Journal of Beijing Forestry University (Vol.12, No.1) in 1990. In this paper, they brought forward that the peony cultivars' classification based on flower forms should follow scientific and the practical principle and built up the "branch-type-form" classification system. In this system, dividing "branch" is based on the phylogenetic relationship; then dividing "type" is based on the number of single flower; dividing "form" is based on the differences of flower's basic structure and petals' double extent. This method divided tree peony cultivars into 5 branches, 2 types, 4 subtypes and 13 flower forms. The main contribution of this method is that it went further and clearly brought forward the composition of branches after Li J.J. set out the multi-origin opinion in 1989. Here, the composition of branches of tree peony is:

—Sufruticosa branch: Containing the single species-derived cultivar-group which evolved from P. jishanensis, and the hybrid cultivar-group which had mainly the ancestry P. jishanensis. In hybrid cultivar-group, they often had the ancestry P. rockii or P. ostii; several cultivars had the ancestry P. qiui. This branch was also called the Zhongyuan cultivar-group.

—Rockii branch: Containing the cultivar-group which evolved from P. rockii and the hybrid cultivars-group which had the ancestry P. rockii. Xibei cultivar-group belongs to this branch.

—Ostii branch: The main original species is P. ostii. The cultivars which evolved from P. ostii are called "Feng Dan" series. Its forming process was affected by Suffruticosa branch. It can normally grow and bloom in moist and hot conditions of the south regions of the Changjiang River, so it is also called the Jiangnan cultivar-group.

—Lutea branch: Containing the cultivar-group which evolved from P. lutea and P. ludlowii and the hybrid cultivar-group which mainly had the ancestry P. lutea and/or P. ludlowii.

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—Delavayi branch: Containing the group which evolved from P. delavayi and the hybrid cultivar-group which mainly had the ancestry of P. delavayi.

Another trait of this method is the treatment of the proliferation. This method divided proliferation into 4 flower form, i.e. primary proliferation, colored proliferation, delaminated proliferation, and globular proliferation according to Qin K. J.' s analysis of proliferation flower's evolutional principle of peonies (1987).

Wang L. Y. 's Classification System

Liu C.Y. and Wang L.Y. (1995) published the research report about the classification method of the herbaceous peony cultivars. According to this report and the former researchers' works, Wang L.Y. advanced a quite detailed tree peony cultivar classification system in the book Chinese Tree Peony in 1997. She divided peony cultivars into 3 series, 4 subseries, 12 groups, 2 sections, 4 subsections and 16 forms.

—The peony cultivars were divided into 3 series and 4 subseries according to the different of section (i.e. section Moutan and section Paeonia) and the original of genus Paeonia: A, tree peony series, divided into tree peony subseries and hybrid subseries of tree peony; B, herbaceous peony series, divided into herbaceous peony subseries and hybrid subseries of herbaceous peony; C, the hybrid series of tree peony and herbaceous peony.

—According to the different of wild protospecies, tree peony cultivars were divided into 12 groups. In these, tree peony subseries were divided into Rockii tree peony cultivar-group and Ostii tree peony cultivar-group. They were pure line cultivar-group. The hybrid subseries of tree peony was divided into 7 groups: (a) Chinese Xibei cultivar-group, (b) Chinese Zhongyuan cultivar-group, (c) Chinese Jiangnan cultivar-group, (d) Chinese Xinan cultivar-group, (e) French Lemoine cultivar-group, (f) American Saunders cultivar-group and (g) Japanese cultivar-group.

—Each group was divided into 2 sections and 4 subsections according to the flower number and the origin of petals: A, single flower section, (a) hundred petals subsection and (b) crown subsection; B, proliferation flower section, (c) hundred proliferation flower subsection and (d) crown proliferation flower subsection.

—Each subsection was divided into 16 forms according to the different petal number or stamen petaloid extent. Here, single flower section contained 9 forms while proliferation flower section contained 7 forms.

This method is the most detailed method which set out the most flower forms by now. Compared with other methods, it has two important characters: One is that it set out pure line cultivar-group based on the composition of the subseries. The other is that each single form has its corresponding proliferation form according to such proliferation flower form' s evolutional character. In these, the descriptions of some flower forms were the same or similar to the Qin K.J.' s proliferation flower classification system. In 1999, the monograph of hong Guo Mu Dan Yu Shao Yao (Chinese tree peonies and herbaceous peonies) was published (Editor in chief, Li J.J.). In this book, Li J.J. revised the classification system which was set down by Qin K.J. and Li J.J. in 1990, and then reset down a new system.

After comparing and analyzing above each classification method, we can get the results: in these methods, the opinions on flower form evolutional principle and the main proofs of flower form classification are almost the same. The differences mainly exist in the treatment of proliferation flower, containing this kind

of flower form' s identifying method and its position in the classification system. About the identifying method, Zhou J.Q. only simply divided it into 2 forms (1962). Later,Qin K.J. (1986) observed earnestly the structure and evolutional process and successively divided it into 4 forms according to the evolutional extent from elementary to advance level. In Wang L.Y.' s system (1997), each single flower form has its corresponding proliferation form. All of these systems which reflected the evolutional relationship from different aspects had their rationality. But in order to facilitate practical utilizing, most researchers are content to simply divided proliferation flower into 2 basic forms, i.e. hundred proliferation and crown proliferation.

Developing Trends

The flower form's classification is the focus in the classification researches of the peony cultivars. The main thing is to make clear of the evolutional relationship among cultivars or groups while other classification methods should not be ignored. Along with the further understanding of cultivar' s biological and commercial characters, other practical classification methods should be paid more attentions.

Classify According to Flower Color and Flower Form Flower color is a quite obvious ornamental character. The classification based on flower color has been using all the time from ancient times. The facts that tree peony' s flower color is variable and there are many secondary colors often bring difficulties to classify. In spite of this the classification which combines flower color with flower form has bigger practical values.

Classify According to Ornamental Characters and Stress-Resistant Characters It is another practical classification, namely evaluating synthetically cultivar' s ornamental characters, combining with the difficult/easy extent of propagation, and then dividing cultivars into several grades to confirm the commercial values. This classification is common used in the produced areas of tree peonies. In the future, the stress-resistant characters (containing cold-, moist- and hot-resistant etc.) should be further analyzed and evaluated in order to facilitate the popularizing and utilizing in different areas.

Other Practical Classifications Set up its utilizing fields by cultivars' biological characters, such as selecting cultivars which are adapt to pot, force culture, cut flower, medicinal use, ornamental and medicinal use etc. In landscape, the combinations of florescence, plant height, stress-resistant, ornamental characters such as flower color and flower form are the vital references for landscape designers. They are the important proofs of introducing and breeding for gardeners in everywhere, too.

4.2 Classification System of Chinese Tree Peony Cultivars

It has always been the struggling target of horticulturists to set up a classification system of tree peony cultivars which can correctly reflect the cultivars origin and the phylogenetic relationships according to the research results of botanic taxonomy and horticultural classification. Li Jiajue et al. did the systematic investigation of tree peony cultivaYs all over the country from 1999 to 2003, and again added and corrected the current popular cultivars classification systems. Latter, he suggested the following classification system of tree peony cultivars alone.

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4.2.1 Classification Principles and Warranties

Classification Principles

The cultivar classification system should correctly reflect the origin and evolutional rules of cultivar-groups and should be easily utilize in practice. The basic principles of this classification system are two points, i.e. scientific combining with practical; mostly emphasizing the evolutional relationship, then complementing of the morphologic characters and practical utilizing.

Classification Warranties

The classification system of Chinese tree peony cultivars set out three classes, i.e. "group", "type", and "form". Their classification proofs are as follows:

The Dividing Warranties of the Groups There are two dividing proofs: one is the composition of original species, the other is the ecological condition. The composition of original species is the base of cultivars classification (Yu D.J. 1985; Chen J.Y. 2001). As talked above (4.1, chapter 4), Chinese tree peonies (contained the introducing cultivars) belong to 5 species-derived systems. They are: (a) Suffruticosa branch, (b) Rockii branch, (c) Ostii branch, (d) Lutea branch, (e) Delavayi branch.

According to the composition of original species and the ecological conditions of the producing areas, Chinese tree peony cultivars can be divided into 4 groups: Zhongyuan, Xibei, Xinan, Jiangnan group. The introducing cultivars belong to Japanese, European and American group.

In theory, each protospecies may form pure line cultivar-group and hybrid group. But in fact, because of the frequent cultivar exchange between different areas and more materials were used in breeding of new cultivars. The phylogenetic relationships of the groups became more and more complex. The pure line cultivar-group which originated from single species is rare (only Rockii cultivar-group and series cultivars of "Feng Dan" which originated from P. ostii), while the hybrid cultivars increases day by day. So there is no division of pure line cultivars and hybrids.

Besides big cultivar-group, there are some smaller cultivar series in different areas. Because of the narrow location areas, they were treated as "subgroup" according to their phylogenetic relationships.

The Dividing Warranties of the Types In each group (or subgroup), tree peony cultivars can be divided into 3 types according to the different origin of petals and flower forms. They are: single petals type, hundred petals type, crown type. Here, in the single flower of the hundred petals type, the asexual petals increase mainly and, in the single flower of the crown type, the sexual petals which were formed by stamen-petalody increase mainly. Because the single flower cultivars increase day by day, it is more suitable to classify them alone.

The single flower is the base of the proliferation flower which evolved from the carpels' heteromorphic development. However, the proliferation flower is similar to single flower in appearance; so you can' t identify the differences without careful observations. In the meantime, a lot of proliferation flower's forms are unsteady because of the effect from such as the cultivar, the ecological environment, and the cultivated methods. So this classification system treats them as subtype. Now there are the single flower subtype and the proliferation flower subtype under both hundred petals type and crown type. So there are 4 subtypes in the whole.

The Dividing Warranties of Flower Forms Tree peony cultivars obey some certain rules in the evolutional course. In the different evolutional phases, it can form a series of different flower forms according to the different evolutional extent and differentiation quantity of the flower organs as well as the differences in the carpel heteromorphic developing extent. The differences in basic structure of flower, double extent and overlap status are the warranties of classifying "flower form", In order to facilitate the practical utilizing, this method considered the following 9 basic forms as first class. They were: single, lotus, chrysanthemum, rose, anemone, crown, globular, hundred petals proliferation, crown-proliferation. And we treated the transitional state' s forms and the proliferation flower forms as the second class. The transitional state's form contains golden-stamen, golden-heart, and golden-circle. In the proliferation flower forms, the hundred petals proliferation contains lotus proliferation subform, chrysanthemum proliferation subform, and rose proliferation subform; and the crown proliferation contains crown (colored petals) proliferation subform, delaminating proliferation subform and globular proliferation subform. The further classification of flower forms is in order to facilitate the researchers' utilizing.

4.2.2 Classification System and its Brief Introduction

After correcting, the classification system of Chinese tree peony cultivars is as Fig.4-1. The brief introduction is as follows.

The Dividing Method of Group

Besides the 4 groups and 2 subgroups which have already existed in China, there were many introducing cultivars from abroad. So in fact, there were 7 groups and 2 subgroups in China.

Chinese Zhongyuan Tree Peony Cultivar-Group This group mainly distributed in the middle reaches and downriver regions of Yellow River; Heze of Shandong and Luoyang of Henan are their cultivated center. P. jlshanensis is the main original species of this group. P.rockii, P. ostii and P.qiui directly or indirectly participate the formation and evolution of this group in different extent by way of crossing with P. jishanensis and its descendants. Here, P. rockii affected the most. In the new cultivars after 1949, some were more close to P. ostii. There are two subgroups in Zhongyuan cultivar-group. They are:

—Yan' an cultivar subgroup, evolved from P. jishanensis and P. rockii subsp. taibaishanica and their hybrid descendants. It located in Yan' an and its vicinity.

—Exi (the west of Hubei) cultivar subgroup, evolved from the crossing of P.rockii, P.ostii and P. qiui. Some cultivars are the domesticated products of Zhongyuan cultivars which transplanted to the south in early times. They distribute in Xiangfan, Baokang, Jianshi of Hubei.

Chinese Xibei Tree Peony Cultivar-Group This group mainly distributed in Gansu, the east of Qinghai, the south of the Ningxia, and the west of Shaanxi. The areas of Lanzhou, Lintao, Linxia, Longxi in Gansu are their cultivated center. This group mainly evolved from P. rockii. Some cultivars came from the crossing of Zhongyuan tree peonies and this group' s cultivars, and they ex-

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Figure 4-1 The sketch map of classification system of Chinese tree peony cultivars based on flower forms

pressed the indirect effect which came from P. jishanensis. In recent years, people also used cultivars of "Feng Dan" series as parents in the breeding procedures of this group, so some cultivars had close relationship with P. ostii.

Chinese Jiangnan Tree Peony Cultivar-Group It mainly distributed in the middle reaches and downriver regions of the Changjiang River, Shanghai, the middle and southern parts of Jiangsu, Southeast of Anhui, North of Zhejiang. Some cultivars in this group mainly originated from P. ostii and directly formed the series cultivars of "Feng Dan". Others came from the domesticate procedure of Zhongyuan tree peony cultivars transferring to south, or from the descendants of these cultivars hybridizing with the cultivars of "Feng Dan" series in the domesticate procedures.

Chinese Xinan Tree Peony Cultivar-Group This group distributed in Southwest China. Pengzhou in Sichuan is the cultivated center. By now, there is no evidence to show that wild species directly participated the forming of this group. According to the historical records and field observation, we thought that the tree peony cultivars of Zhongyuan and Xibei were transferred to South China, then domesticating, hybridizing, evolving and finally formed this group.

Japanese Tree Peony Cultivar-Group It mainly distributed in Japan. Japanese introduced Chinese Zhongyuan tree peony cultivars and then formed the group which had notable characters through long term domesticating, crossing, breeding, improving and selecting according to their aesthetic sentiment.

European Tree Peony Cultivar-Group France and England are the main producing areas. This group contains some Zhongyuan tree peony cultivars which were domesticated by local climate and the hybrid descendants of P. lutea and P. ludlowii.

American Tree Peony Cultivar-Group American successively introduced tree peony from England, France, Japan and China. This group is a hybrid group which came from the repetitious crossing of the wild species such as P.delavayi, P. lutea and the introduced cultivars (most were Japanese tree peony cultivars).

The Dividing Method of Type

Single Petals Type They are commonly primal and simple flowers without petal increasing. The pistils and stamens are fertile.

Hundred Petals Type The flowers are flat. The petals increasing of single flower mainly comes from the natural increasing of asexua petals or combine with the forming of sexual petals. The petals have similar shape; and they delaminate and gradually become smalle: from outside to inside. There are no stamens between petals tiers. The stamens in the flower center decrease or increase. Carpels are norma. or extremely increase or even heteromorphicly develop into the proliferation flower.

Single Flower Subtype in Hundred Petals Type This subtype consists of single flower belonging to the hundred petals type There is no the superposing phenomenon of two-flowers or many-flowers.

Proliferation Flower Subtype in Hundred Petals Type In this subtype, the lower-flower is single flower belonging to the hundred petals type. The whole flower consists of two-flowers or formed through many-flowers superposing.

Crown Type The middle parts of this flower upheave like crown. The outside petals are often wide and round. The middle petals mainly originate from stamen's petalody. Most of them folded as undulant shape. There are many petals. Thej arrange tightly and upheave upward. The remained stamen; are often found between petals. The remained anthers can be found in the end of petals. The stamens decrease while the petaloids increase. Carpels are normal or petaloid or extremely increase and, they develop heteromorphicly into the proliferation flower.

Single Flower Subtype in Crown Type This subtype consists of crown single flower. There is no superposing phenomenon of " two-flowers " or " many-flowers ".

Proliferation Flower Subtype in Crown Type In this subtypes

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the lower-flower is crown single flower. The whole flower consists of two-flowers or formed through many-flowers superposing.

The Dividing Method of Flower Form Single Petals Type

1 Single Form. The petals are 2 layers; seldom 3 layers. Generally pistils and stamens are fertile. The phenomenon of the stamens extremely decreasing or the pistils increasing is rare.

1a Golden-Stamen Form. The petals are 2 layers. Stamens are large (anther is corpulent, filaments stretch out). Pistils are fertile.

Hundred Petals Type Single Flower Subtype in Hundred Petals Type

2 Lotus Form. The petals are 4-5 layers, big and similar with each other in shape and size. Pistils and stamens are fertile. Several stamens are petaloid or decreasing.

3 Chrysanthemum Form. The petals are 6-8 layers and gradually become smaller from outside to inside. Stamens are fertile; decreasing or several petaloid in the middle of flower. Stamens rarely increase. Carpels are normal, rarely petaloid or degenerate.

4 Rose Form. The petals are over 9 layers or extremely increasing, gradually become smaller from outside to inside. Stamens decrease or remained in the middle of flower and mixed some stamen-derived petaloids. Stamens rarely extremely increase. Carpels are normal or degenerate and become smaller or the number increasing.

Proliferation Flower Subtype in Hundred Petals Type

5 Hundred Petals Proliferation Form. The whole flower consists of 2 or over 2 flowers. The lower-flower is hundred single flower. This form contains the following subforms:

5a Lotus Proliferation Subform. The lower-flower is lotus form. Carpels are normal or lightly petaloid. The developing extent of the upper-flower is different in different cultivars.

5b Chrysanthemum Proliferation Subform. The lower-flower is chrysanthemum form. Carpels are lightly petaloid or whole petaloid. The developing extent of upper-flower is different in different cultivars.

5c Rose Proliferation Subform. The lower-flower is rose form. Carpels are petaloid or vestigial. The developing extent of the upper-flower is different in different cultivars. Most are 2 flowers, seldom 3 flowers.

Crown Type

—Single Flower Subtype of Crown Type

6 Anemone Form. The outer petals are wide and unfold, arranging in 2 - 3 layers. Most or all stamens are petaloid. The petaloids are narrow and long, straight or contorted. They are remarkably smaller than outer petals. There are partial anther remained in petaloids in some cultivars. Carpels are normal.

6a Golden-Heart Form. The outer petals are 2 - 3 layers, wide and unfold. Many stamens surround pistils. Outer stamens form several/many layers of petals which are different in size. Carpels are normal or lightly becoming petalody.

7 Crown Form. The outer petals are 2 or many layers, wide and unfold. Most or all stamens are petaloid. Petaloids are straight and upheave. The petaloids near the middle part of flower are wide while the petaloids near out petals are narrow or remained anthers. There are several fertile or degenerate stamens mixed with petaloids. Carpels are normal or petaloids.

7a Golden-Circle Form. The outer petals are 2 - 3 layers, wide and unfold. Most of stamens are petaloid. And the petaloids upheave. A circle of fertile stamens remained between petals.

and petaloids Carpels are normal or petaloid.

8 Globular Form. All stamens are highly petaloid and such petaloids are similar to outer petals in shape and size. Carpels are normal or increase in number; or some are petaloid becoming to green-petals (inserting green); or some degenerate and become smaller or even disappear. The whole flower is buxom and full like globular.

—Proliferation Flower Subtype in Crown Type

9 Crown-Proliferation Form. The whole-flower consists of 2 or over 2 flowers. The lower-flower is single flower of crown form. This form contains the following subforms:

9a Crown Proliferation Subform. It is also called the colored petals proliferation subform. The lower-flower is crown form. Carpels are petaloids which are mostly color-petals with greenish color or with green strips.

9b Delaminating Proliferation Subform. The lower-flower' s petaloids from carpels are the same with normal petals, so it is difficult to distinguish such two kinds of petals. The stamen-derived petaloids are smaller and shorter than outside petals. The upper-flower's petals are wide. The inner petals are short. Carpels are petaloid or degenerate. The whole flower has notable delami-nating structures. Most consist of 2 flowers, several consist of 3 flowers. Consisting of 4 flowers is rare.

9c Globular Proliferation Subform. The petaloids of lower-flower's stamens are similar to normal petals when stretching out or unfolding. The carpel-derived petaloids are similar to normal petals, too. The upper-flower's petaloids are similar to normal petals. Carpels are petaloid or degenerate. The whole flower shows globular.

4.2.3 Some Issues in the Application of Classification System Based on Flower Forms

The Different Evolutional Extent of Various Cultivar-Group A good flower form' s classification system should suit most horticultural cultivars. This system was advanced based on the sufficient investigations and analyses of tree peony cultivars' evolutional process in China and abroad, so it had adaptability in large-scales. However, there were many differences in evolutional extent of each cultivar-group, for example, Chinese Zhongyuan, Xinan and Jiangnan cultivar-group had higher evolutional extent while Xibei cultivar-group had relatively lower evolutional extent; and there were only several flower forms and without proliferation form in Yan' an subgroup. So the classification system should base on the practice and objectively reflect the evolutional levels of each flower form or group in different areas.

The Identification of Proliferation Form

In flower form' s classification, it is hard to distinguish proliferation form, especially the highly evolutional cultivars. The pistil-derived petaloids are almost the same as normal petals. It needs careful observations and analyses of flower structure; especially the changes of the number of floral discring on the receptacle should be paid more attention. Single flower has one ring of disc; multi-flower (proliferation form) has two or more rings; and the floral disc over the second ring mostly was sejunct; each carpel had its corresponding floral disc. But in the delaminating proliferation form, sometimes the traces of carpel-derived petaloids and floral disc can' t be seen. It can be judged by the changes of shape and size

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of the petal trace on the receptacle. Generally, the trace of outer petals is long strip while the trace of stamen-derived petaloids is smaller and like spots.

The Treatment of Several Flower Form Phenomenon of One Cultivar

Many cultivars have several flower form phenomenon because of the nutritional differences of different parts of single plant. In these, single flower and proliferation flower coexisting are common to see. Generally, such change is accordance with flower form evolution and can reflect the variational extent of flower form of the same cultivar. We could observe the phenomenon, namely there were lotus,

chrysanthemum, rose, hundred petals proliferation in the flower form' s changes of the same cultivar. However, the hundred petals proliferation form appeared only in the hundred petals type; and the crown-proliferation form cultivar appeared only the above flower form changes in the crown type. But the flowers of single form or lotus form may appear in crown-proliferation form cultivars, and such evolutional relationship has been expressed in Fig.4-1. The flower form description of certain cultivar should put the flower form which had the highest evolutional extent in the first place, and at the same time record the form which had the highest appearance frequency and its range of flower form variation.

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