Journal of University of Chinese Academy of Sciences

Endemism in the Flora of China—Studies on the Endemic Genera

Ying Tsün-Shen, Zhang Zhi-Song

1984, 22 (4): 259-268.

Abstract ( 0 )

China, under highly varied ecological conditions resulted from wide lati-

tudinal and altitudinal ranges and from the adequate precipitation, has developed a

very rich flora of great diversity. As far as flowering plants are concerned, there are

2980 genera, 214 of which, belonging to 64 families, are endemic. Among these ende-

mic genera, there are 9 genera of taxads and conifers, 19 genera of monocots and

others of dicots. Of the approximately 129 herbaceous endemic genera in the Chinese

flora as a whole, about 22 (17%) are annual and 107 (83%) are biennial or perennial.

In the present paper the ecological distribution, the nature of endemic genera and the

centers of endemism are discussed.

1. Three types of endemic genera are distinguished, neoendemics, palaeoendemics

and active epibiotics, The endemic genera in the flora of China are, for the most part,

considered to be very old ones, and most of them are of temperate nature.

2. the degree of endemism in our 22 floristic regions is shown in Figure 1. The

areas richest in endemic genera in the Chinese flora as a whole are the 13, 16 and 17

regions. The poorest are the 2, 4, 9 and 10 regions, and no one in the 1 and 3 regions

These results on floristic richness are of general applicability.

As shown in table 1, the difference in the degree of endemism among the seven

Chinese floristic subkingdoms are most pronounced. 101 endemic genera are known

to occur in one subkingdom, 72 to occur in two subkingdoms, and 3 to occur in four

subkingdoms, only one genus widely distributed in five subkingdoms. However, there

is no genus occurring in seven subkingdoms. The difference in the degree of endemism

in each subkingdom reveals that the distribution of endemic genera is not well-distri-

buted in the Chinese flora as a whole.

Analysis of the vertical distribution of the 200 endemic genera of the Chinese

flora bears out that there is no evident increase in endemism as a whole with altitude.

3. Three centers of endemism are found (Fig. 2). These are as follows:

a). Eastern Sichuan-western Hubei center.

b). Southeastern Yunnan-western Guangxi center.

c). Western Sichuan-northwestern Yunnan center. The degree of endemism and

characters of endemic genera in each center are discussed.

On the Systematic Position of Amentotaxus from Its Embryological Investigation

Chen Zu-Keng, Wang Fu-Hsiung

1984, 22 (4): 269-276.

Abstract ( 0 )

The present paper deals with the embryological study and the systematic

position of Amentotaxus argotaenia (Hance) Pilger. The material used was collected

during 1980-1981 from Jin-fo Shan, 1400-1600 m, Sichuan Province, China. The

species is dioecious. The male cone sheds its pollen during the period from the end of

May to the middle of June. The pollen at mature stage is 2-celled. Pollen chamber

appears obvious at the end of the nucellus. When pollen grains are dispersed, megas-

pore mother cell, which is situated deep in the nucellus, is in meiosis. The megaspore

divides mitotically after pollination and the free nuclei of female gametophyte divide

for the last time at the end of June. The wall formation takes place at the stage of 256

free nuclei. The development of archegonia takes place at the beginning of July and

the fertilization occurs about July 20-23. The fertilized egg divides successively

four times and results in a 16-nucleate proembryo. The young embryo is developing in

August. It is interesting to note that the development of the young embryo is very

slow. When the seed reaches the mature stage from June to July in the following

year, the multicellular masses of the young embryos resulted from simple polyembryony

remain immature within the female gametophyte. No cleavage polyembryony has been

found. The subsequent embryogeny takes place after the seed has shed.

Keng (1975) considers that Amentotaxus links the Taxaceae with Cephalotaxaceae.

Our embryological data support Keng’s conclusion since they share (1) compound

microstrobilus, (2) 2-celled pollen grains at shedding stage and (3) the rather long

life cycle. Keng (1975) also mentions that Podocarpaceae may connect with Taxaceae

through Phyllocladus. According to Keng the Podocarpaceae is related to Taxaceae to

certain degree. It is obvious that the primitive spike-like male strobilus like the one

in Cordaitales is obviously retained in Podocarpus spicatus and P. andinus of Podocar-

paceae and Amentotaxus of Taxaceae. In addition, like in Amentotaxus there are 16

nuclei before wall formation in the proembryo of Podocarpus nivalis. These facts may

well indicate that at least the Podocarpaceae and the Taxaceae were derived from a

common stock. As far as the Taxaceae is concerned the authors tend to support the

view of Koidzumi (1932) that Amentotaxus and Austrotaxus should be put in the same

tribe since both possess the spike-like strobilus, the long life cycle and the seed matura-

tion in the following year. They are probably rather primitive genera in the Taxaceae.

The proembryogeny of Torreya is more or less specialized. It may be placed in a ra-

ther advanced tribe and the tribe Taxeae (including Taxus and Pseudotaxus)may be

between the above two tribes. In conclusion, the Taxaceae is related to the Coniferales

in certain respects and, as Keng (1975), Harri (1976) and Wang et al. (1979) have

pointed out recently, placing of the Taxaceae in Coniferales is rather justifiable.

A Study on the Genus Cephalotaxus Sieb. et Zucc.

Fu Li-Kuo

1984, 22 (4): 277-288.

Abstract ( 0 )

The genus Cephalotaxus contains a small number of species. It is adequately

appreciated as a newly discovered cancerresistant medicament for the alkaloids obtai-

ned from its branches leaves and barks are of curative effect.

This paper deals with the classificatory revision based on the morphological featu-

res, with the reference to the anatomical characters of leaves, types of alkaloids and

pollen morphology observed. Two new combinations are proposed, and 4 species and

varieties are reduced in the paper. The genus Cephalotaxus is thus suggested to consist

of 2 sections and 9 species. The trees occur in East Asia and the north of Indo-China,

with 88% found in China where is the distribution centre and refuge of the genus.

The genus in discussion is of unique morphological features which are distinctly dif-

ferent from these of Amentotaxus, Cephalotaxaceae, containing a single genus of Ce-

phalotaxus, is closely related to Taxaceae, and therefore the Cephalotaxaceae is best

placed in the Taxinieae of Coniferales.

Comparative Anatomy of the Leaves of Cephalotaxus (Cephalotaxaceae)

Hu Yu-Shi

1984, 22 (4): 289-296.

Abstract ( 0 )

The internal structure and cuticular characters of the leaves of Cephalota-

xus were investigated under light microscope and scanning electron microscope. The

materials used belong to 9 species, 2 varieties and 1 cultivar.

The leaf characters of C. oliveri Mast. are as follows: stomata are amphicyclic

and occasionally monocyclic, the stomatal frequency is 120.6/mm², the hypodermis is

present, there are a large number of filiform sclereids and a few brachysclereids and

astrosclereids in the mesophyll, the cuticular projections on the lower surfaces are in-

distinct. This species differs from all the other species of Cephalotaxus, in which

stomata are amphicyclic only, the stomatal frequency is 47.3-88.1/mm², hypodermis

is absent except in C. harringtonia and C. harringtonia cv. ‘Fastigiata’, foliar astroscle-

reids, hrachysclereids asd fibriform selereids may be present or entirely absent, there

are distinct cuticular projections on the lower surface. Based upon the above-mentioned

features, the gross morphology as well as the alkaloids. Cephalotaxus may be divided

into two sections, namely: Sect. Cephalotaxus and Sect. Pectinatae.

In addition, also discussed are following problems: the classification of some species

in Sect. Cephalotaxus, the suggested subdivision of Sect. Cephalotaxus into 4 series,

and the systematic position of Cephalotaxaceae.

Pollen Tetrads in Lilium with a Discussion on the Delimitation Between L.semer vivoideum and Its Ally

Liang Song-Yun, Zhang Wu-Xiu

1984, 22 (4): 297-300.

Abstract ( 0 )

In the course of our palynological study on the Chinese Lilium, pollen

tetrads are found in two taxa of the genus: L. sempervivoideum and L. amoenum. The

latter is distributed in NW. and S. Yunnan Province. It was established by Wilson,

but reduced later by himself to a synonym of L. sempervivoideum which occurs from S.

Sichuan to C. Yunnan. However, it is regarded as a species distinct from the former by

many authors, such as Sealy (1949), Woodcock and Stearn (1950) and S. Y. Liang

(1980).

Their pollen tetrads are similar in aperture appearance and sexine patterns, but

different in the shape, size and arrangement of sculptural elements, as shown by LM

and SEM examination. Their leaf shape and flower colour are different, though there

are some transitions between them. Based on the facts mentioned above, it is reason-

able to regard the two taxa as two subspecies in L. sempervivoideum.

Chromosomes of Six Fabaceous Species from Baoxing County, Sichuan Province

Hong De-Yuan

1984, 22 (4): 301-305.

Abstract ( 0 )

Meiosis and/or mitosis of six species of Fabaceae (Leguminosae) from

Baoxing County, Sichuan, China, were investigated. The voucher specimens are con-

served in PE. Eight pairs (n=8) and 10 chiasmata in meiosis of pollen mother cells

have been observed in Medicago lupulina L. (Pl. 1, A-C). Meiotic observation on

pollen mother cells in Lotus tenuis W. et K. shows 6 bivalents (n=6) in MI and 9 chias-

mata in diakinesis (Pl. 1, D-E). In this species 12 somatic chromosomes (2n=12) in

anther wall cells have also been observed. The chromosomal formula may be expressed

as 2n=12=8m+2sm+2sm^SAT (Pl. 1, F-G). In pollen mother cells of Vicia tetrasperma

(L.) Schreb., 7 bivalents in MI and 7 chromosomes in A II have been observed (Pl. 2,

A-B). From A II (Pl. 2, B, the inset on the right) the chromosomal formula, n=7=

2m+2sm+lst^SAT+2t, may be constructed. Only three chromosomes in this karyotype may

be found to have counterparts in the one reported by Srivastava (1963), which shows

striking differences between these two karyotypes. Meiotic MI shows 7 pairs (n=7)

in Vicia hirsuta (L.) S. F. Gray. Vicia sativa L. is very variable in its chromosomes.

Our observation shows 6 pairs (n=6) in MI and in diakinesis in pollen mother cells.

In Vicia villosa Roth, all the previous chromosome reports are 2n=14 or n=7, but the

result of our work shows that somatic chromosomes are 2n=12 in anther wall cells

(Pl. 3, D, E). The karyotype in our material (Pl. 3, E) is that the longest pair of chro-

mosomes are metacentric, the pairs 2-4 are terminal, 5 are metacentric and last pair

are submetacentric, differing vastly from the idiogram (Pl. 3, F) presented by Yama-

moto (1973). Therefore both the chromosome number and structure in our material

are greatly different from those in all the previous reports.

The evolutionary trends of chromosomes in the genus Vicia is discussed in the

work. Srivastava (1963) holds that the primitive basic number of chromosome in the

genus is 6 and thus both 5 and 7 are derived. The present author would propose ano-

ther possibility that 7 is the original basic number and the other numbers are derived

ones. First, as shown in Table 1, x=7 occurs in 47 per cent of species in the genus,

but 6 only in 28 per cent. Secondly, x=7 is predominant in the perennial and primitive

section Cracca. Thirdly, in genera related to the genus under consideration, such as

Lens, Pisum and Lathyrus, x=7 is also the predominant basic number. Fourthly, ac-

cording to Raven (1975) 7 is the primitive basic number in the angiosperms and x=

7, 8 and 9 are the predominant in the angiosperms.

Notes on the Genus Isachne R. Br. of China

Fang Wen-Zhe

1984, 22 (4): 306-311.

Abstract ( 0 )

The present paper involves descriptiins and discussions of some doubtful

species in the genus Isachne. One species and two varieties are new, another species is

newly reported from the main land of China, and the delimitation and rank of the

other three species are reinvestigated and ascertained.

New Species of Orchidaceae from Western Sichuan, China

Lang Kai-Yung

1984, 22 (4): 312-315.

Abstract ( 0 )

Two New Species of Rhododendron Linn

Hu Lin-Cheng

1984, 22 (4): 316-318.

Abstract ( 0 )

New Taxa of Boraginaceae from China

Liu Yu-Lan

1984, 22 (4): 319-320.

Abstract ( 0 )

Some New Green Algae from Xizang (Tibet)

Wei Yin-Xin

1984, 22 (4): 321-336.

Abstract ( 0 )

Some New Taxa of Euglenophyta from Xizang (Tibet)

Shi Zhi-Xin

1984, 22 (4): 337-342.

Abstract ( 0 )

A New Variety of Dalbergia fusca Pierre

Zou Shou-Qing, Liu Jian-Hua

1984, 22 (4): 342-342.

Abstract ( 0 )

Current Issue