On the Fossil Pediastrum from the Gaoximage Section, Hunshandak Sandy Land and Its Ecological Significance Since 5 000 a BP

The fossil Pediastrum was investigated from the Gaoximage section ( 42°57′14″ N, 115°22′3″E, Air 1 253 m ) in the Hunshandak Sandy Land, Inner Mongolia (Nei Mongol) of China in order to gain a better understanding the changes of palaeovegetation, palaeoenvironment and palaeoclimite since 5000 aBP when the pollen-spore was studied. The results show that the fossil Pediastrum assemblage can be divided into three periods: Ⅰ. 5 000-3 500 a BP, the fossil Pediastrum occurred rarely. Based on this result it can be surmised that the lake might be fresh water with poor organics. Ⅱ. 3 500-1 500 a BP, the fossil Pediastrum likes volcanic emerged. It probably indicate moist conditions and the grasslands were developed during this time; and Ⅲ. 1 500-200 a BP, the fossil Pediastrum disappeared. It can show that the lake water become salty and shrunk, and the weather could become drier and drier. This result shows that Pediastrurn, a kind of facies fossil, happened simultaneously in the pollen-spore assemblage during the second period. Sometimes Pediastrurncan reach more than 60 per cent of the total spore pollen assemblage, indicating that Gaoximage lake was not only fresh water with abundant eutrophic materials but also occupied a large area during 3 500-1 500 a BP.

A revision of Clematis sect. Aspidanthera s.l. (Ranunculaceae)

In this paper Clematis sect. Aspidanthera s.l. is revised. Seventy_ two species and 15 varieties are recognized. They are keyed, described, and in most cases illustrated, and are classified into six subsections. Of them, on e series, five species, and two varieties are described as new, and two new rank s are proposed. Brief taxonomic history and geographical distribution of the sec tion are given, the evolutionary trends of several important morphological characters observed are e numerated, and the relationships of its subsections are discussed. As a resul t, subsect. Dioicae, which shows striking resemblance in both habit an d floral structure to sect. Clematis subsect. Clematis, is regar ded as t he primitive group, while subsect. Insidiosae, bearing pistillate flower wit h erect sepals and no staminodes, is regarded as the advanced group within the s ection.

Loss of Genetic Diversity of Domesticated Panax notoginseng F H Chen as Evidenced by ITS Sequence and AFLP Polymorphism： A Comparative Study with P. stipuleanatus H T Tsai et K M Feng

In the present study, we evaluated the genetic diversity of Panax notoginseng F H Chen, a domesticated species, and P. stipuleanatus H T Tsai et K M Feng, an endangered wild species in southeastern Yunnan and adjacent areas in Vietnam, using sequences of the internal transcribed spacer (ITS) regions of nuclear ribosomal DNA and amplified fragment length polymorphism (AFLP) markers. Twenty-four accessions from three plantations of P. notoginseng and 51 samples from eight populations of P. stipuleanatus were assayed. A total of 694 bp of partial sequences of 18S, ITS 1, 5.8S, ITS2, and partial sequences of 26S were obtained. No sequence variation was detected within P. notoginseng and nine sites (1.30%) were variable in P. stipuleanatus. Two-thirds of the variable sites were found between Langqiao and other populations. In P. notoginseng, four pairs of AFLP primer combinations generated 312 bands, of which 240 (76.9%) were polymorphic and 60.15% of the polymorphisms were harbored within plantations. Approximately 41.0% and 66.9% of bands were polymorphic in population D7 and 5589, respectively. In P.stipuleanatus, the same four primer combinations produced 346 bands, of which 334 (96.5%) were polymorphic and approximately 62.14% of polymorphisms were maintained within populations. Considerable variations were observed. The percentage of polymorphic bands ranged from 50.2% to 84.9% and the average over populations was 70.9%. Cluster analysis did not show correlation of genetic differentiation with the distinctive leaf morphology of P. stipuleanatus (i.e. one form with bipinnatifid leaflets and the other with undivided leaflets). Because over 40% of genetic variations were maintained among populations and because of the very restricted distribution of P. stipuleanatus, all natural populations of this species should be conserved in situ. Considering that there are variations in P. notoginseng within and among plantations, we suggest establishing a genetic resource conservation garden or reintroducing P. notoginseng into its native habitats in southwestern China. Such reintroduction should be carefully executed after large-scale screening of genetic variation within the species.

Phylogeny and Biogeography of Thuja L. （Cupressaceae）, an Eastern Asian and North American Disjunct Genus

: In order to develop better insights into biogeographic patterns of eastern Asian and North American disjunct plant genera, sequences of nuclear ribosomal DNA internal transcribed spacer (nr DNA ITS) region were used to estimate interspecific relationships of Thuja L. (Cupressaceae) and infer its biogeography based on the phylogeny. According to the phylogenetic analysis, two clades were recognized. The first clade included Thuja plicata D. Don (western North America) and T. koraiensis Nakai (northeastern Asia), and the second one contained T. occidentalis(Gord.) Carr. (Japan). The ancestral area of Thuja was inferred to be eastern Asia, and two dispersal events were responsible for the modern distribution of Thuja in North America. Both the North Atlantic land bridge and Bering land bridge were possible routes for the migration of ancestral populations to North America.

Conifer Woods of the Pliocene Age from Yunnan, China

Abstract: The Tertiary floras play an integral role in understanding the biodiversity and interactions between climate and vegetation in Yunnan, China. The fossil spores, pollen grains, and leaves in this region have been investiaged intensively. In comparison, the woods have been studied relatively little. A large number of Pliocene wood specimens was collected from the opencast lignite coal mine of Hongxing situated in Changning County of Yunnan Province. Among the collection, Tsuga cf. dumosa (D. Don) Eichler and Pinus cf. armandii Franchet were identified based on wood structures. The subtle feature of tori extensions is reported in the wood of T. cf. dumosa. Considering the climatic requirements of modern T. dumosa and P. armandii, the two species of conifer described from Pliocene sediments probably grew in mountainous terrain at an elevation of approximately 2 300 m, in a cool and humid environment.

Floral Morphogenesis of Anemone rivularis Buch.-Ham. ex DC. var.flore-minore Maxim. （Ranunculaceae） with Special Emphasis on Androecium Developmental Sequence

: The floral morphogenesis and androecium developmental sequence of Anemone rivularis Buch.-Ham. ex DC. var. flore-minore Maxim. were observed under a scanning electron microscope (SEM) and by means of histological methods in order to expand our knowledge of the morphogenesis and development of the floral organs of the Ranunculaceae. The initiation of the floral elements is a centripetal spiral and the direction of the spiral is clockwise or anti-clockwise. However, the development of the androecium is highly unusual: in a longitudinal series of four stamens, the second stamen develops first from the inner to outer, then the third one, the fourth one and the first one in turn. The microsporogenesis and anther maturation follows the same developmental sequence. The tepals are different from the bracts and the stamens in both shape and size in the early developmental stage, but there is no difference between the stamens and carpels in the early developmental stage. Therefore, we established a spatio-temporal process of the floral morphogenesis of A. rivularis var. flore-minore and offer another meaning of the floral diversity patterns attributed to the level of the genus.

Bolboschoenus （Ascherson） Palla （Cyperaceae） from Pliocene of China

Tubers, culms, rhizomes, and leaves of Bolboschoenus cf. yagara (Ohwi) YC Yang et M Zhan were reported from the sediments of Zhangcun Formation, Late Pliocene in Shanxi Province, China. The fossil species possesses trigonous culms. And tubers are cordiform, spindle shaped, or round, and are covered by roots in internodes and often connected by rhizomes. This is the first convincing fossil record of Cyperaceae in China.