In the present paper seven distribution patterns in west-east direction and eight in

southwest-northeast direction found in the Eastern Asiatic Region (Taxta  ЛЖЯΗ 1978) are

discerned,and the taxa belonging to each of these patterns are enumerated. Some of these

taxa are analysed geographically or/and phylogenetically. Clematis brevicaudata and C.

ganpiniana,Aconitum sinomontanum var. sinomontanum and A. sinomontanum var. angustius,

Thalictrum alpinum and T. squamiferum, Adonis brevistylus and A. sutchuenensis, Ostryopsis

davidiana and O. nobilis, Corylus heterophylla var. heterophylla and C. heterophylla var.

sutchuenensis, C. ferox var. ferox and C. ferox var. tibetica, Carpinus cordata and C. fangiana,

Cyclobalanopsis glauca and C. glaucoides, Decaisnea fargesii and D. insignis, Elatostema

obtusum and E. medogensis, Corylus sect. Corylus and sect.  Acanthochlamys, Prinsepia sect.

Prinsepia and sect. Plagiospermum, Corylus and Ostryopsis, Hilliella and Yinshania (Zhang

1986, 1987), ,Actinidia and Clematoclethra (Tang and Xiang 1989), Peracarpa and Homocodon

(Hong 1983) etc. are all regarded as sister groups and might have differentiated in Southwest

China. According to the geographical distribution and the affinities, the following taxa might

be considered to have originated in Southwest China: Salix wallichiana, S. paraplesia and S.

cheilophila (Zhou, Fang et al. 1984),Aristolochia debilis (J. S. Ma 1989),Aconitum

hemsleyanum (L. Q. Li 1988), Semiaquilegia adoxoides (Hsiao et al. 1964), Dichocarpum

adiantifolium (D. Z. Fu 1988), Thalictrum baicalense, T. alpinum var. elatum, Anemone

flaccida, A. baicalensis, A. hupehensis, A. tomentosa, Clematis henryi, C. lasiandra, C.

montana, Corydalis curviflora, Chrysosplenium griffithii, C. uniflorum (Pan 1986), Parnassia

foliosa (Ku 1987), Tetrastigma obtectum (Gagnepain 1911), Actinidia kolomikta, A. polygama

(Liang 1983, 1984), Incarvillea sinensis (Grierson 1961), Paris polyphylla (H. Li et al. 1988),

etc.. The genera Dichocarpum (D. Z. Fu 1988),Loropetalum, Corylopsis (Harms 1930; Chang

1979), Stachyurus (Chen 1981; Tang et al. 1983), Helwingia (Hara and Kurosawa 1975),

Aucuba (Hara 1966；Soong 1982；X. W. Li 1987), Enkianthus and Cardiocrinum (Kanai 1966)

with the typical eastern-Asiatic distribution pattern and with either the distribution center or

the primitive group in Southwest China are also considered to have arised there. According to

the fact that the distribution centers of the genera Elatostema (Wang 1980), Hemiboea (Z. Y.

Li 1987), and Lysionotus (Wang 1983) are situated in southeastern Yunnan and western

Guangxi, Elatostema involucratum, Hemiboea henryi, and Lysionotus pauciflorus might origi-

nate there and from there migrated northeastewards to East China or Japan respectively. On

the basis of the 15 distribution patterns and the analyses just given, three migration routes

may be recognized, i. e. (1) the route extending from Southwest China eastward along the

Qinling Range and the Dabie Range in the north, which may be named as the Qinling-Dabie

Corridor, along the Nanling Range in the south, which may be named as the Nanling Corri-

dor, and along other mountain chains in Central China to East China or Taiwan province of

China, and eventually to Japan, (2) the route running from Southwest China westwards to the

Himalayas, which has been named as the Himalayan Corridor (Kitamura 1955), and (3) the

route stretching from the Hengduan Mountains northeastwards through the Qinling Range,

the eastern fringe of the Loess Plateau including the Taihang Range, the Yinshan Range, the

Changbai Mountains and the Xiao Hinggan Mountains to Siberia or/and the adjacent re-

gions. The last route may be named as the Chinese southwest-northeast Corridor, being the

passage for various floristic elements migrating from Siberia or Northeast China

southwestwards to Southwest China and vice versa during the Quaternary Ice Ages (Wang

1989). According to the geographical distribution of Hemiboea henryi and Lysionotus

pauciflorus (Gesneriaceae, Wang Fig. 2, 1983), that of Chirita anachoreta and Aeschynanthus

acuminatus (Gesneriaceae, Wang, Fig. 5, 1985), that of Chirita pumila, Lysionotus serratus,

Aeschynanthus superbus, A. bracteatus, Rhynchotechum vestitum (Gesneriaceae, Wang, Fig. 2,

1983, 1985), Elatostema laevissimum, E. balansae, E. macintyrei (Urticaceae, Wang 1980),

Tetrastigma serrulatum (vitaceae, Wang 1979), and Alcimandra cathcarthii (Magnoliaceae,

Wu and Wang, Fig.  1,  1957), that of Euchresta (Leguminosae), Bennetiodendron

(Flacourtiaceae), Rhopalocnemis phalloides (Balanophoraceae, Steenis, Fig. 4, 1935; Wu and

Wang,  Fig.  6,  1957),  Thalictrum javanicum  (Ranunculaceae),  Elatostema  backeri,

Chamabainia cuspidata, and Droguetia pauciflora (Urticaceae, Wang 1989), and that of

Caryodaphnopsis (Lauraceae, Wu and Wang, Fig. 5, 1957; H. W. Li 1979), distinguished may

be additional five migration routes, i. e. (1) the route extending from southeastern Yunnan

and western Guangxi northeastwards to East China and Japan, (2) the route running from

the southern Yunnan-Guizhou Plateau eastwards along the Nanling Corridor to Taiwan

province of China, (3) the route stretching from the southern Yunnan Plateau and the north-

ern Indo-China westwards along the southern and western margins of the Yunnan Plateau to

southeastern Xizang (Tibet) or/and Assam, and along the Himalayan Corridor eventually

to Nepal, (4) the route extending from the same regions just mentioned southwards through

the Malayan Peninsula to Sumatra and Java, and (5) the route stretching from the same re-

gions also southeastwards through Borneo to the Philippines. The analyses and the radiant

pattern of the migration routes mentioned above lead me to agree with the important argu-

ments that in Southwest China “the important parts of the original flora of China evolved”,

and “the Sino-Himalayan region has the richest alpine flora of the world” (Li, 1944), that the

Chinese flora without any doubt, is not only the foundation of the other floras of eastern

Asia, but also the origin of many floristic elements of temperate regions (Wulff, 1944), and

that the flora of South and Southwest China and the Indo-Chinese Peninsula, being most

rich in archaic families and genera and being derived from the palaeotropical flora, has given

rise not only to the temperate and subtropical floras of eastern Asia, but also to those of

North America and Europe (Wu, 1965). The facts that in Yunnan Province occur about 2110

genera and 13900 species of the angiosperms (Wu et al. 1984; H. W. Li 1985) and in the

Hengduan Mountains “no less than 1500 genera and perhaps more than 10 thousand species” (Wu 1988), 

and that located in Southwest China is the center of endemism of China (Ying

and Zhang 1984; H. S. Wang 1985), and the palaeobotanical evidence that the temperate flo-

ras appear to have differentiated by the Middle Cretaceous (Berry 1937; Axelrod 1952;

Takhtajan 1969), further lead me to speculate, though in the absence of fossil data, that the

Yunnan-Guizhou Plateau plus Sichuan Province might be an important center of develop-

ment of the angiosperms in the Northern Hemisphere once by the Middle Cretaceous and a

strong evolutionary radiation might have taken place there, which resulted in the formation

of the migration routes described above from this center to various regions in various direc-

The development or adaptation radiation of angiosperms has been closely related

to the paleoclimate and paleoenvironment. Several environmental factors, influencing each

other, have affected the evolution or development of angiosperms, which falls into different

stages. The lines between these stages are not consistent with the traditional geological ages.

Floristic regionalization might be better based on the stages of the development.

     Angiosperms have become important or dominant elements in the flora since the middle

and late period of the Late Cretaceous. The development of angiosperms may be divided into

four stages: (1) Initial stage: The angiosperms were not yet well established during the Early

Cretaceous. The number of species and individuals was limited, the leaf small, mostly with en-

tire margine, irregular venation and poor differentiation of venation; (2) Flourished stage:

The angiosperms increased dramatically and became abundant. The leaf was larger with

more regular venation and the differentiation of venation was remarkable. The percentage of

angiosperms was from 40%-60% in the flora, and eventually arose, becoming predominant,

with important families well presented. This was probably from the Late Cretaceous to the

Early Tertiary; (3) Herbs-Flourished stage: Some of woody plants were extinct, while herbs

greatly increased, because of the changes in climate, sea level and mountain uplift during the

Neogene period; (4)Quaternary stage: The mountain glacier in China, influenced by global

glacial-interglacial alternation due to the climatic fluctuation, advanced and regressed during

the Quaternary. The climatic fluctuation apparently affected the distribution of plants. But

the components of the flora were similar to or slightly different from the features of the pres-

ent one.

     The aim of the present paper is to discuss the floristic regions at the second and third

stages.

     The Late Cretaceous-Early Tertiary stage:

     A. The Late Cretaceous-Paleogene flora of northern China

     1. Warm-temperate to subtropical deciduous broad-leaved and conifer forests in North

and Northeastern China

     2. Dry subtropical flora of Northwestern and Central China

     B. Southern China Late Cretaceous-Paleogene flora

     3. Deciduous and evergreen forests with coniferous elements in the subtropical coastal

region of east China

     4. Evergreen forests of South China

     5. Evergreen forests of lower mountains in the Tethys

     The Neogene stage-Herbs-flourished stage:

     1. Temperate forests and grasslands to semidesert-desert floras of northwestern China;

     2. Warm temperate deciduous forests of north and northeastern China;

     3. Warm temperate to subtropical deciduous and evergreen forests of central and east

China;

     4. Evergreen forests of the subtropical and tropics mangrove vegetation of south China;

The present paper discusses the classification, distribution, systematic relationship

and origin of the genus Euchresta Benn.

     Euchresta is distributed roughly in East and Southeast Asia. The Chinese name “Shan-dou-gen”(山豆根) first appeared in “The Medicinal Herbs of Sichuan “(蜀本草) in the Song Dynasty. Afterwards there were accounts of this name in “A Materia Medica of kaibao”（开宝本草）, and “The Illustrated Classic Herbal”(图经本草) by Su Sung (苏颂). In the MingDynasty, “Shan-dou-gen” was adopted in “ Materia Medica with Commentaries” (本草纲目) by Li Shih-chen (李时珍)^［1］and it has recorded for quite a long time until now. However, because the root of Euchresta japonica Hook. f. ex Regel. is a Chinese medicine used for detoxification, and relieving pain and pharyngitis, many medicinal plants, whose roots have the same effect, are also called  “Shan-dou-gen” . They are Arcisia (Myrsinaceae), Cyclea, Pericampylus, Stephania, Menispermum (Menispermaceae), Helicteres (Sterculiaceae) , Beesia (Ranunculaceae) , Sarcococca (Buxaceae) , Sophora,

Atylosia (Leguminosae), etc. However, the name should be used only for Euchresta japonica according to the Chinese botanical literature.

      The genus was established by J. J. Bennett in 1838, based on Andira horsfieldii Lesch.  (1810)  ( =E. horsfieldii (Lesch.) Benn.) from Java, It was classified in the subtribe Geoffroeeae of the tribe Dalbergieae by Bentham (1860) and Bentham et Hooker (1865). There were two species then, i. e. E. horsfieldii and E. japonica. In 1970-1978, H. Ohashi and

his co-workers published a series of outstanding works on Euchresta, in which H. Ohashi established a new tribe-Euchresteae Ohashi, that contains only one genus-Euchresta, and suggested a clearly close relationship between the genus under study and the tribe Sophoreae, especially Sophora, and also considered that the ancient group of Euchresta was in between New Guinea and Australia and extended northwestwards to islands and the continent of Asia. He described 4 species and reduced two species, i. e. E. trifoliolata Merr. (1922) from Guangdong, China (=E. japonica) and E. strigillosa C. Y. Wu. Wen (1984) published E. longiracemosa S. Lee et H. Q. Wen ex H. Q. Wen from Guangxi, China, as new. Five species are included so far in this genus. This paper reports 4 species and 3 varieties: i. e. E. japonica, E. horsfieldii, E. horsfieldii var. laotica, E. formosana, E. tubulosa, E. tubulosa var. longiracemosa, and E. tubulosa var. brevituba, which are grouped into two sections (Fig. 3). i. e. Sect. Euchrestae and Sect. Tubulosae. Sect. I. Euchrestae without a long tube at the base of calyx, comprises 3 species, 1 variety and is distributed in southern Honshu of Japan, southern Yunnan of China, northern Indochina Peninsula, and Java of Indonesia. The section forms three discontinuous distribution patterns: 1) E. japonica is of Sino-Japanese discontinuous distribution; 2) E. horsfieldii is of Himalayas-Indochina-Java discontinuous distribution; 3) E. formosana is of Taiwan-Ryukyu-Philippines discontinuous distribution (Fig. 2). From what has been stated above, this section may be the primitive group, of which E. horsfieldii and E. formosana have evolved from E. japonica. Sect. II, Tubulosae, with a long tube at the base of calyx, comprises 1 species, 2 varieties and forms an island disjunction with its centre in Hubei, Hunan and Sichuan of China. The two sections are considered to have stemed from

the same extinct primitive group and developed along different directions, with the distribution centre in Central and South China (Fig. 3)

     There are many opinions on the systematic position of Euchresta. Bentham and Hooker (1865) placed it in the tribe Dalbergieae. Baker ( 1878), Nakai (1940) and Hutchinson (1964) holded Bentham and Hooker’s opinion, while Nakai (1940) established a subtribe, Euchrestinae Nakai, and considered Euchresta related to Mullera Linn. F. and Andira A. L. Juss. According to the morphological, cytological and biochemical data, Ohashi (1970-1978) clearly suggested a close relationship between the tribe Euchresteae and the tribe Sophoreae, which are different from the genera in the tribe Geoffroeeae as well as the tribe Dalbergieae (s. l.). He also recognized the similarity between Euchresta and Sophora, especially S. bhutanica and its allied species. Polhill and Raven (1981) holded Ohashi’s opinion, but the relationship of the tribe Euchresteae was put between the tribe Crotararieae and the tribe Thermopsideae hermopsideae, far from the tribe Sophoreae. We agree with Ohashi, but we think that Euchresta is most closely related to the genus Maackia, especially judged from the chromosomal number and the chemical composition, which is in accordance with M. Tenuifolia (Hemsl.) Hand. -Mazz. ( Mizuno et al. 1990). Therefere, the relationship of Euchresta with its allied genera is suggested as in Fig. 4.

  Based on the habitat and distributional area of Euchresta, it is inferred that its ancestor was a member of the Tertiary-paleotropical mountain forest flora and then distributed in the whole forest region. It is considered that the genus originated in Cathaysia.

     The distributional area of Euchresta lies in the area west of “Wallace’s Line”, a famous biogeographic line. Many botanists and zoologists have discussed this line, but they have also proposed many modified biogeographic lines for this area (Brown and Gibson 1983) e. g. “Huxley’s line” (including modifications); “Sclater’s line”(1858); “Weber’s line” (1902); “Lydekker’s line”;  Merrill’s line” (1923) etc., (Fig. 2), of which “Wallace’s Lin” and “Lydekker’s line” are accepted by many zoogeographers. However, Schuster (1972) expounded “Wallace’s line”based on more pieces of evidence from geology, zoography, and distribution of land plants (including Hepaticae, Conifers, and Angiospermae). Thus Schuster

stated: (1) The narrow channel between the Australian bloc and Eurasian one was still an effective barrier for many groups of organisms as recently as 10-15 m. y. ago. (2)The amount of movement-or transgression-across this barrier varies from group to group. Organisms -presumably  “modern” and “successful”-with strong powers of movement have trans-

gressed to a larger extent than taxa belonging to old, “senescent”and (usually) stenotypic groups. Thus it can be said that Euchresta is an age-older group and distributed only in the area west of “Wallace’s Line”. It is also known from the information of paleogeography and paleobiogeography: up to about 50 m. y. ago Australia and New Guinea moved progressively northward from warm temparate into the tropics, crossing the Tropic of Capricorn at about

the beginning of the Miocene (25 m. y.), and coming into more or less direct contact with the proto-Indonesian at the middle Miocene (-15m. y.) (Axelrod & Raven, 1982). At that time, Euchresta was only distributed in Asia (including Philippines and Java) and formed the present dispersal-patterns, but it has never reached New Guinea and Australia (i. e. southeast of

During investigating rare and endangered plants in China, the authors made

morphological observation on Hamamelis subaequalis H. T. Chang and discovered that it is

apetalus, different from the tribe Hamamelideae, in addition to other morphological charac-

ters,  which  differ  from  the  genera  of the  tribes  Distylteae  and  Fothergilleae

 This paper reports chromosome numbers and karyotypes of five species of the ge-

nus Fritillaria from south Anhui. The origin of the material used in this work is provided in

Table 1, micrographs of mitotic metaphase in Plate 1,2, and the parameters of chromosomes

in Table 2. Except F. thunbergii Miq., the karyotypes and chromosome numbers of all the

species in this paper were studied for the first time. The results are shown as follows:

     1. Fritillaria qimenensis D. C. Zhang et J. Z. Shao

     Collected from Qimen, Anhui, it has the karyotype formula 2n = 24+4Bs = 3m+lsm+8st

(2sc)+12t (2sc)+4Bs (Plate 1:1, 2). The chromosomes range in length 8.72-19.13μm, with the

ratio of the longest to the shortest 2.19. Therefore, the karyotype belongs to Stebbins’

(1971) 3B. The secondary constrictions are found on the long arms of 7th and 10th pairs. All

the five B-chromosomes are of terminal centromeres. The two chromosomes of the second

pair show heteromorphy (Fig. 1, E) with arm ratios 1.86 and 1.56 respectively.

     2. Fritillaria monantha Miq. var. tonglingensis S. C. Chen et S. F. Yin

     Collected from Tongling, Anhui, this species is shown to have three chromosome num-

bers, 2n =24+5Bs, 2n=24+2Bs and 2n=24. This paper reports 2 cytotypes: Type I:

2n = 24+5Bs = 4m+8st (2sc) +12t (2sc) +5Bs (Plate 1: 3, 4). The chromosomes range in length

from 10.40 to 22.19μm, with the ratio of the longest to the shortest 2.13. It belongs to 3B of

stebbins’(1971) karyotypic symmetry. The secondary constrictions are found on the short

arms of 7th and the long arms of 9th chromosome pairs. The metacentric B-chromosomes

and the small satellites located on the short arms are major characters of this cytotype. Type

II: 2n=24=2m+2sm+8st(2sc)+12t(2sc) (Plate 1:5, 6). The chromosomes range in length

from 13.84 to 29.81μm, with the ratio of the longest to the shortest 2.15. The karyotype be-

longs to Stebbins’3B. The secondary constrictions are found on the long arms of 5th and

10th pairs. No B-chromosomes are found.

    3. Fritillaria xiaobeimu Y. K. Yang, J. Z. Shao et M. M. Fang

     Collected from Ningguo, Anhui, it has karyotype formula 2n = 24 = 2m+2sm+10st (4sc)

+ 10t (Plate 2:7, 8). The chromosomes range in length from 13.86 to 26.27μm, with the ratio

of the longest to the shortest 1.89. The karyotype belongs to stebbins’3A. The secondary

constrictions are found on the long arms of 7th and 9th pairs.

     4. Fritillaria ningguoensis S. C. Chen et S. F. Yin

     Collected from Ningguo, Anhui, it is of karyotype formula 2n = 24 = 2m+2sm+8st (2sc)

+12t (Plate 2: 9, 10). The chromosomes range in length from 9.11 to 23.23μm, with the ratio

of the longest to the shortest 2.55. The karyotype belongs to Stebbins’3B. The secondary

constrictions are only found on the long arms of the 10 th pair.

     5. Fritillaria thunbergii Miq.

     Collected from Ningguo, Anhui, it is of karyotype formula 2n = 24 = 2m+2sm+8st(2sc)

+12t(2sc)(Plate 2:11, 12). The chromosomes range in length from 8.83 to 19.85μm, with the

ratio of the longest to the shortest 2.25. The karyotype belongs to stebbins’3B. There are

secondary constrictions on the long arms of 5th and 7th pairs. The karyotype of the Ningguo

material is similar to that of the Huoqiu (Anhui) material reported by Xu Jin-lin et al.

(1987), but it is obviously different from 2n=2m(sc)+2sm+4st(2sc)+16t (2sc) reported by

This paper deals with karyotype analysis of three taxa of Fritillaria, i. e. F.

thunbergii (from Yinxian and Zhoushan), F. thunbergii var. chekiangensis, and F. anhuiensis.

The results show that all the three taxa are diploid (2n = 24) and their karyotypes are differ-

ent. The karyotype formulae may be summarized as follows: F. thunbergii: Yinxian, 4m(lsc)

+4st(lsc) ^l) +16t(lsc) ; Zhoushan, 2m+2sm+12st(lsc) +8t(2sc) . F. thunbergii var.

chekiangensis2m+2sm+8st (2sc) +12t (4sc). F. anhuiensis 2m+2sm+8st (2sc) + 12t (５sc). There

are many secondary constrictions in all the three taxa of Fritillaria studied, but the number

Pollen morphology of 25 Chinese species, representing 6 five genera in the tribe

Rhamneae of Rhamnaceae, was examined under LM and SEM. Pollen grains are

subspheroidal or suboblate, obtuse-triangular in polar view, 3-colporate, with the polar axis

(P)10.4-28.7μm long and equatorial axis (E) 11.3-30.5μm long, P/E = 0.81-1.11. Colpi

generally narrow and long, ora lalongate, with two ends connected with the thinned part of

exine, forming a H-shape. Four thickenings were observed where colpi and ora cross, but

sometimes the thickenings were indistinct or formed a ring. The stratification indistinct. The

ornamentation of exine obscure or indistinctly reticulate under LM, but rugulose,

short-striate, rugulose-foveolate or reticulate under SEM.

     The exine ultrastructure of Rhamnus ussuriensis was examined under TEM. It consists of

imperforate tectum, granular layer, foot layer and endexine. The tectum is rather thick with

uneven surface, while the granular layer is rather thin.

     A key to the genera based on pollen characteristics is provided and the general

pollenmorphology of five genera, i.e. Sageretia, Rhamnus, Hovenia, Colubrina and Alphitonia,

is described respectively.

      Based on pollen size, the four thickenings and the ornamentation, the five genera under

study may be distinguished from each other. For example, pollen grains are smaller in

Sageretia; the four thickenings are larger and distinct in Hovenia and Alphitonia. However,

the ornamentation is short-striate under SEM in Hovenia and Alphitonia, while reticulate in

the Colubrina and Rhamnus ( Subgen. Rhamnus) .Two different concepts of Rhamnus exist

among taxonomists. Heppeler and Suessenguth divided Rhamnus into two subgenera

(Subgen. Frangula and Subgen. Rhamnus), whereas Grubov separated Subgen. Frangula

from Rhamnus as an independent genus. According to the pollen morphology, the separation

seven new taxa of the genus Delphinium (Ranunculaceae) are described from

Xinjiang, China. They are Delphinium yechengense; D. pseudocyananthum; D. eglandulosum;