Journal of University of Chinese Academy of Sciences

On Primary Subdivisions of the Magnoliophyt—Towards a New Scheme for an Eight-class System of Classification of the Angiosperms

WU Zheng-Yi, TANG Yan-Cheng, LU An-Ming, CHEN Zhi-Duan

1998, 36 (5): 385-402.

Abstract ( 0 )

The current subdivision of the angiosperms into two major groups, the dicotyle-

dons and the monocotyledons, whether at the rank of class or subclass, is greatly challenged

by more and more evidence from comparative morphology, chemotaxonomy, paleobotany,

cladistics and molecular systematics. It becomes clear that this primary subdivision is conven-

tional rather than natural. We stressed in this paper that the system of classification of the

angiosperms should be as much as possible based on the geneaological relationships of major

groups. It seems apparent that eight principal lineages appeared by the end of the Early Cre-

taceous when the one of the major radiation of the angiosperms occurred. By using the Lin-

nean hierarchy, these lineages are named at the rank of class in order to reflect major evolu-

tionary trends within the angiosperms. As evolutionary systematists, we accepted para-

phyletic' groups as natural in this scheme. The eight classes are as follows: Magnoliopsida

(including Degeneriaceae, Himantandraceae, Magnoliaceae, Winteraceae, Canellaceae, Illi-

ciaceae, Schisandraceae, Austrobaileyaceae, Eupomatiaceae, Annonaceae, Myristicaceae,

Hydropeltidaceae, Cabombaceae, Nupharaceae, Nymphaeaceae, Barclayaceae, Ceratophyl-

laceae), Lauropsida (including Amborellaceae, Trimeniaceae, Monimiaceae, Gomorte-

gaceae, Hernandiaceae, Lauraceae, Calycanthaceae, Idiospermaceae, Chloranthaceae),

Piperopsida ( including Aristolochiaceae, Saururaceae, Piperaceae, Lactoridaceae ),

Caryophyllopsida(including Caryophyllaceae, Molluginaceae, Aizoaceae, Amaranthaceae,

Chenopodiaceae, Halophytaceae, Stegnospermataceae, Achatocarpaceae, Phytolacaceae,

Nyctaginaceae, Cactaceae, Portulacaceae, Didiereaceae, Basellaceae, Hectorellaceae), Lil-

iopsida( including the families of Liliopsida sensu Takhtajan ( 1997 ) ), Ranunculopsida ( in-

cluding Ranunculaceae, Lardizabalaceae, Sargentodoxaceae, Menispermaceae, Circaeaster-

aceae, Nandinaceae, Berberidaceae(incl. Ranzaniaceae), Leonticaceae, Podophyllaceae, Hy-

drastidaceae, Glaucidiaceae, Paeoniaceae, Pteridophyllaceae, Papaveraceae, Hypecoaceae,

Fumariaceae, Nelumbonaceae), Hamamelidopsida(including Trochodendraceae, Tetracen-

traceae, Cercidiphyllaceae, Eupteleaceae, Myrothamnaceae, Hamamelidaceae, Pla-

tanaceae), and Rosopsida(including the families of Rafflesianae, Balanophoranae, Hamame-

lididae p. p., Dilleniidae, Rosidae, Cornidae, Lamiidae, Asteridae sensu Takhtajan

(1997)). Principal families in each class are discussed here. Further study is needed to eluci-

date the phylogenetic relationships among and within the classes.

The Systematic Position of Beesia: Evidence from ITS (nrDNA) Sequence Analysis

WANG Xiao-Quan, DENG Zheng-Rong, HONG De-Yuan

1998, 36 (5): 403-410.

Abstract ( 0 )

Discussed in the present paper is the systematic position of Beesia, a small ranun-

culaceous genus mainly distributed in SW China. Sequences of the internal transcribed spac-

ers (ITS) and 3’ end of 5.8 S rRNA gene of Beesia calthifolia, Trollius chinensis, Cimi-

cifuga acerina, C. brachycarpa and Actaea asiatica were determined by direct PCR se-

quencing method. The sequences of ITS-1 in the five species range from 225 bp to 232 bp in

size and those of ITS-2 from 201 bp to 217 bp. Beesia is very similar to Cimicifuga and Ac-

taea not only in size, sequence and G+C content of ITS, but also in sequence of 3’ end of

5.8 S rRNA gene. In PAUP analysis, Ranunculus enysii was used as outgroup, and the

most parsimonious tree was obtained through exhaustive search. The gaps were treated re-

spectively as missing characters and the fifth base in two analyses. The two analyses show

that a monophyletic group comprising Beesia calthifolia, Cimicifuga acerina, C. brachy-

carpa and Actaea asiatica is strongly supported by the bootstrap value. In the monophyletic

group, Beesia calthifolia is basal to the other three species. The present DNA sequence

analysis demonstrates that the genus Beesia should be placed in the tribe Cimicifugeae,

which is consistent with the results from phytochemistry, palynology and cytology. In addi-

tion, Beesia may be the most original genus in the tribe Cimicifugeae in view of simple leaf,

apetalous flower and molecular evidence.

A Revaluation of the Systematic Positions of the Cercidiphyllaceae and Daphniphyllaceae Based on rbc L Gene Sequence Analysis, with Reference to the Relationship in the “Lower” Hamamelidae

FENG Yu-Xing, WANG Xiao-Quan, PAN Kai-Yu, HONG De-Yuan

1998, 36 (5): 411-422.

Abstract ( 0 )

The rbcL gene sequences of six species representing five subfamilies of the

Hamamelidaceae and the Platanaceae were determined and used in the phylogenetic analysis

on the “lower” Hamamelidae sensu Endress (1989) and its allies newly suggested. Four most

parsimonious trees were obtained, all having 893 steps with CI = 0. 558 and RI = 0. 591.

The families Cercidiphyllaceae, Daphniphyllaceae, Hamamelidaceae and Saxifragaceae are

closely located, while the relationships among them remain unsolved even if more representa-

tives of the Hamamelidaceae were further added in this parsimony analysis. Our results con-

firm the phylogenetic trees revealed by Chase et al. (1993) and Soltis et al. (1997), instead

of those of Hoot and Crane (1996). Considering the morphological features they share, it is

suggested that the Cercidiphyllaceae and Daphniphyllaceae be placed into the Hamamelidales.

The relationship between the Platanaceae and the Hamamelidaceae shown in our analysis is

not so closed as suggested by the cladistic analyses by using morphological characters only(e.

g. Lu et al., 1991), while those among the Platanaceae, Trochodendraceae and Tetracen-

traceae are close as indicated by this study. The Eupteleaceae falls into the Ranunculales.

The Eucommiaceae seems to show closer relationship with the Hamamelidaceae, the “core”

family of the “lower” Hamamelidae, than with the other members except the Cercidiphyl-

laceae. The rbcL gene trees imply that the “lower” Hamamelidae is a heterogeneous group,

composed of isolated ancient families.

Kingdonia, Embryology and Its Systematic Significance

REN Yi, WANG Ma-Li, HU Zheng-Hai

1998, 36 (5): 423-427.

Abstract ( 0 )

The embryological studies show that Kingdonia is similar to Circaeaster while

different from other members of the Ranunculales (sensu Takhtajan, 1980) in development of endosperm and embryo. We consider that there is close systematic relationship between Kingdonia and Circaeaster.

Development of Ovules and Embryo sacs in Ostrya virginiana (Betulaceae) and Its Systematic Significance

XING Shu-Ping, CHEN Zhi-Duan, LU An-Ming

1998, 36 (5): 428-435.

Abstract ( 0 )

The development of ovules and embryo sacs in Ostrya virginiana was studied for

the first time. Most ovaries had two ovules which were anatropous, unitegmic and crassinu-

cellate. The ovule usually possessed several archesporial ceils which divided periclinally into

the upper parietal cell and the lower sporogenous cell. The sporogenous cell functioned di-

rectly as megaspore mother cell. The tetrad of megaspores was linear in arrangement, and

every megaspore might be functional. One ovule often contained 2- 6 embryo sacs and the

embryo sac belongs to Polygonum type. It can be concluded from the present data that all

ovules among the genera of the Betulaceae are unitegrnic. There are more groups with the

phenomenon of multiple embryo sacs in anemophic plants such as Betulaceae, Casuarinaceae,

Graminae, Jnglandaceae, Myricaceae, Simaroubaceae, Ulmaceae, than in entomophilous

plants. Multiple embryo sacs also occur among some parasitic plants and saprophytes, e.g.

Orobanchaceae, Cassytha in Lauraceae, Cuscuta in Convolvulaceae and Utricularia in Len-

tibulariaceae. It may be inferred that the characteristic of multiple embryo sacs be an evolu-

tionary adaptation of those plants with lower pollination rate to increase the rate of fertiliza-

tion. Finally, a comparison of embryological characters among the genera of the Betulaceae

shows that the family is of a number of common embryological characters, such as multicellu-

lar archesporium, multiple embryo sacs in one ovule, and a long interval between pollination

and fertilization. The diversity and systematic significance of several embryological characters

among the “higher” hamamelid families are also discussed. It is still hard to explain the phy-

logenetic relationships among those families clearly only with.

A Study on the Spore Morphology of Bryum Hedw. in China

DU Gui-Sen, WANG Mei-Zhi, ZHANG Yu-Long

1998, 36 (5): 436-440.

Abstract ( 0 )

Spore morphology of thirteen species of the genus Bryum Hedw. were observed

by LM and SEM. The results show that the ornamentation of spore exine could be divided

into three types: Type I , blunt at the top of baculate processes, to which four species be-

long: Bryum argenteum, B. lonchocaulon , B. uliginosum and B. arcticum. Type Ⅱ,

sharp or with small processes at the top of baculate processes, represented by seven species:

B. pallescens, B. caespiticium, B. pallens, B. pseudotriquetrum, B. paradoxum, B.

alpinum and B. thomsoii. Type Ⅲ, expanded into hemispherical-shaped at the top of bac-

ulate processes, represented by two species: B.coronatum and B.sauteri. The

Bryum species may also be divided into three groups according to the variation of spore diam-

eter. Group I , with spore diameter under 10 μm, including one species, B. uliginosum.

Group Ⅱ, with spore diameter 11～20 μm, including seven species: B. argenteum, B.

alpinum, B. coronatum, B. pallens, B.paradoxum, B.sauteri, B.thomsonii.

Group Ⅲ, spore diameter 21～30 μm, with five species: B. pallescens, B. caespiticium,

B. pseudotriquetrum, B. lonchocaulon, B. arcticum. There are resemblances of spore

morphology and exine ornamentation among the thirteen species. In the view of palynology,

the genus Bryum is a natural taxon which is more advanced than the genus Pohlia Hedw.

But spores of thirteen species are different at some characters such as diameter, shape of

proximal leptoma, etc., which indicates the genetic differentiation in the genus Bryum.

SEM Observation on the Structure of Cuticles on Leaf Inner Surface of Abies (Pinaceae) and Its Significance in Systematics

XIANG Qiao-Ping, FU Li-Kuo

1998, 36 (5): 441-448.

Abstract ( 0 )

Comparative investigation of the inner surface of the needle cuticle of 36 species

and 2 varieties of Abies under SEM has revealed that the characteristics of the intercellular

flanges are rather distinct and four types can be distinguished: (1) Straight and developed

single flange. This type is only represented by Abies bracteata D. Don. Morphologically,

this species is also quite unique in the genus Abies and was once treated as a subgenus by

Franco and Liu. Its special structure of the leaf cuticle observed here seems to support their

treatment. (2) Double flanges. This type was first discovered in a leaf fossil of Abies from

England. In modern plants of Abies, it is found only in the species from Central America.

(3) Undeveloped single flange. This type is represented by a small group of Abies from the

west and east coastal area of the Pacific Ocean. (4) Undulate and developed single flange.

This type is represented by most of the species of Abies, including all the species in Europe

and most species in Asia and North America. The flange types mentioned above seem to have

some relationships with the geographical distribution of the species in the genus Abies, and

their occurrence might have not been completely influenced by the habitats, hence the fea-

tures of the intercellular flanges may provide good evidence for the subgeneric division of

Abies. Based on our results and those from the previously published literature about the infra-

generic treatments of Abies and the distribution of the fossils, we consider that western

North America might be the diversity center of modern Abies. Florin once pointed out that

the characters of the leaf cuticle in gymnosperms are of great significance for the generic and

infrageneric division. This viewpoint is strongly supported by our study on modern Abies.

A New Subgenus of Platanthera (Orchidaceae)

LANG Kai-Yong

1998, 36 (5): 449-458.

Abstract ( 0 )

Platanthera L. C. Rich. subgen. Stigmatosae K. Y. Lang proposed in Lang's

“Studies on the distribution patterns of some significant genera in orchid flora” in 1994b is

published in the present paper. The new subgenus includes twelve species with one new com-

bination, P. edgeworthii (Hook. f. ex Collett)K. Y. Lang, which are all enumerated

here.

Two New Species of Crawfurdia (Gentianaceae) from Xizang (Tibet), China

ZHENG Wei-Lie, YAO Kan

1998, 36 (5): 452-462.

Abstract ( 0 )

A New Species of Mougeotia from China

ZHENG Hong-Ping, CHEN Zhuo-Hua

1998, 36 (5): 463-464.

Abstract ( 0 )

New Materials of the Fern Genus Polystichum Roth. from Western China

ZHANG Li-Bing, KUNG Hsian-Shiu

1998, 36 (5): 465-468.

Abstract ( 0 )

A New Curtivated Variety of Taiwania cryptomerioidis

LAN Kai-Min

1998, 36 (5): 469-469.

Abstract ( 0 )

The Species Problem in Plant Taxonomy in China

HSU Ping-Sheng

1998, 36 (5): 470-480.

Abstract ( 0 )

Nooteboom (1992) and Peter Raven (pers. comm. ) have pointed out that Chinese

taxonomists often hold a narrow species concept and that this may due to the small volum of

collections, especially type specimens, available to them which led to the unadequate study

on the variability of the species. Raven remarked that “this leads me to believe that the actu-

al concept of species used in plant systematics in China tends to be fairly typological”. What

they said are by no means unreasonable. Indeed, the taxonomical status of a considerable

number of species in the Chinese flora is probably open to question. New species based on a

single character or solely on vegetative characters are of frequent occurrence. Evidences from

a very limited number of researches on the patterns of plant variation heretofore available in

China have shown that some “species” are, in fact, ecological races ( Clinopodium ), geo-

graphical races (Cunninghamia & Indigofera ), or taxa with topoclinal variation (Les-

pedeza & Rhododendron ). Species based on plasticity of phenotype variation have been or

still regarded as “good species” ( Rorippa ). Segregates of an interspecific hybrid with diverse

leaf characters have been given different species names ( Ilex ). The originally complicated

situation in taxonomy of an agamic complex becomes even more complicated after the publi-

cation of additional new species (Malus). A careful analysis of a species with rather compli-

cated patterns of variation leads to the combination of 25 specific names, of which 10 were

published in the 80’s by Chinese taxonomists ( Clematoclethra ). Examples of these kinds

will greatly increase with the broadening of research work at the species level.

Orthodox plant taxonomy is based largely or solely on morphological characters. The ex-

omorphic characters have the practical advantage that they are relatively easy to observe and

to record. The taxonomical species concept can meet the needs of general purpose classifica-

tion. But the notion that the taxonomical species concept is a solely intuitive judgement or

preference of an individual worker and one could hardly say what is right and what is wrong

is quite problematical. The species category today is much more capable of objective interpre-

tation than ever before. A correct species concept stems from a correct and thorough under-

standing of the nature of variation pattern of plants and its taxonomical value. Hence, as a

herbarium taxonomist, the first thing is to study as many collections as possible. Secondly,

the incorporation of evidence from other sources whenever possible is highly desirable. These

evidences,if they are not very useful as taxonomical criteria, are frequently of great signifi-

canee in contributing to a better understanding or interpretation of the variation pattern of a

given taxon. The taxonomist might find the discontinuities he seeks better expressed in ei-

ther the phenotypic or the genetic variation. A logical application of these two sorts of criteri-

a would lead to a more rational classification at the specific level in a great many genera.

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