Two new triterpenoid saponins, namely prostratoside D and E, were isolated from the whole plants of Polycarpon prostratum (Forssk.)Aschers. et Schwein. ex Aschers.By spectroscopic methods, their structures were determined as 3-O-{β-D-xylopyranosyl-(1→2)-β-D-glucopyranosyl-(1→4)-[β-D-glucopyranosyl-(1→2)]-a-L-arabinopyranoside}-saikogeninD和3-O-{β-D-xylopyranosyl-(1→2)-β-D-glucopyranosyl-(1→4)-[β-D-glucopyranosyl-(1→2)]-α-L-arabinopyranoside}-saikogenin G,respectively.

A new flavonoid glycoside,3',4'-dimethoxy-5,7,5＇-trihydroxyl-flavone-3-O-α-L-rhamnopyranoside(1)and four known flavonoid glycosides were isolated from the arerial part of Clausena exavata(Rutaceae),collected from Xishuangbanna, Yunnan, P R China.The 13C NMR assignments for the C6 and C8 of the four known compounds 2-5 were revised by means of 2D NMR experiments.

A systematic study on the growth, development, dry matter production and partition of maize sowing in different seasons were made in the town of Caoba of Mengzi in 1996-1997.The results are as follows:1. The growth duration of winter maize is 171 days, the summer maize growth duration is only 101 days.2.Spring maize produced more dry matter after silk. There is a an direct correlation between the amount of dry matter production and the product of sunshine-hour multiplied by the leaf area index.

This paper dealed with the growth and development properties of the de-virus carnation seedlings The tissue culture seedlings and xuttaging seedlings that infected by carnation mottle virus were used as control. The results indicated that the de-virus seedlings were obviously better than those of the control on most of leaf, and the dry matter weight of root, stem and leaf during the seedling period. The quality indexes such as the diameter of bud and flower, the height and width of stem during flowering period were also much better than those of the control. Furthermore, the yield of the virus-free seedlings can be improved and the period of growth and developmert can be shortened greatly.

The mature pollen of peanut (Arachis hypogaea L.) is bicellular and tricolpate. The exine is faveolate. The pollen wall comprises of tectum, bacula, nexine and intine. The vegetative cell cytoplasm contains large amount of mitochondria, extensively distributive rough endoplasmic reticulum, numerous lipid bodies and plastids containing starch grains.The mitochondria are clustered, with many parallel cristae. The rough endoplasmic reticulum associates with not only the outer nuclear membrane but also the mitochondria. Lipid bodies are surrounded by rough endoplasmic reticulum. Few dictyosoes were observed. The vegetagenerative cell shows a wall, spindle-shaped with a long and tail-like extension (8um long) at one end. It is difficult to determine whether a similar extension is at the other end for lack of using serial sectioning. The generative cell cytoplasm contains mitochondria, ribosomes and microtubles but no plastid. The globular bodies with double membranes, a few cristae and dense inclusions are found within some generative nuclei. Their origin and nature are unknown and need to be further studied.

The pollen grains of 27 native and introduced species belonging to 18 genera of Bignoniaceae were examined by light and scanning electron microscopes. Some of which were reported or examined by scanning electron microscope for the first time. Thought, the Bignoniaceae are conspicuously, their apertures can be divided into 3(-4) colpate, 3(-4)colporate, 3-porate, stephanocolpate types. The exine sculptures include foveo-late, rugulate, reticulate (fine and coarse reticulations) and spinulate, or psilate. Most pollen grains exist as monads but a few are tetrad. In the genus of Radermachera, the pollen aperture and sculpture are different between R.sinica and R.yunnanensis. The pollen of R.sinica is 3-porate and sculpture are different between R.sinica colpate and foveolate sculpture. In the family of Bignoniaceae, the pollen morphology is valuable both in generic delimitation and in the study of systematic relationships, especially aperture and the exine sculpture.

The chromosome numbers and karyotypes of 7 species in Ligularia are reported in this paper. The results are as follows: 2n=-2x=58=28sm+4st for L.kanaitszienis; 2n=2x=58=26m+32sm for L.stenocephala; 2n=2x=58=26m+32sm for L.stenocephala; 2n=2x=58=26sm+2st for L.hookeri; 2n=2x=58=28m+26sm(2sat)+4st for L.latihastata; 2n=2x=58=26m+28sm+2st+2t for L.dictyoneura

The genetic diversity and population differentiation of an endemic Dipterocarp, Vatica guangxiensis, were examined using allozyme analysis of horizontal sliceable starch gel electrophoresis. It is dintributed in Mengla of Southern Yunnan and Napo of Southwest Guangxi only. Aallozyme data for 23 loci of 14 enzymes indicated low level of genetic diversity with the proportion of polymorphic loci(P) ranging from 13.0% to 21.7%, average mumber of alleles per locus (A) from 1.1 to 1.2, average expected (He) and observed (Ho)heterozgosity per locus from 0.056 to 0.130 and 0.055 to 0.130,respectively.

The soil seed banks in the soil of 10 cm and seedling banks of shrubland in Tiantong Range, Zhejiang Province were studied in this paper by using methods of sampling quadrats and germinating. The results showed that the seed densities in the litter layer, 0-2 cm, 2-4cm and 4-10cm were 125.0 seeds/m2, 134.3 seeds/m2,84.6 seeds/m2 and 62.7 seeds/m2 respectively. The dominant species of the seed banks were mainly herb plants, e.g. Lophatherum gracile, Miscanthus sinensis, Carex sp., and some shrub plants, e.g. Symplocos sumuntia, Loropetalum chinese and Quercus fabri. It could be drawn from the studeis on the seedling bank that the dominant species, such as Castanopsis sclerophylla, Ardisia japonica and Lophatherum gracile, were not outstanding.

Through a comprehensive study of all Melocalamus specimens from Yunnan, it is reported here that the record of M.compactiflorus in Yunnan was misidentified because other species was cited when described. Meanwhile, a new status (M.compactiflorus var. fimbriatus) is made and its floral characteristics is outlined. Up to now, two species and one variety of Melocalamus are identified in Yunnan. A key to species is provided.

Two national second-class protected plant species, Calocedrus macrolepis and Pseudotsuga sinensis are mainly distributed in Yimen County, Yunnan Province. These two species and two communities dominanted by Calocedrus macrolepis and Pseudotsuga sinensis respctively are believed to be very valuable in conservation. They have become the first nature reserve in China focusing on the conservation of these two species only. The study on the characteristics of community, its floristic constitution and the population composition of these two species shows the urgency of conservaation.The natural distribution has been limited because Calocedrus macrolepis is a shade tolerant tree while Pseudotsuga sinensis is shade intolerant. Calocedrus macrolepis is regarded to be originated from the central and central-southern part of Yunnan based on fossils evidences. The habitat of Calocedrus macrolepis tends to prefer a more tropical climate than that of Pseudotsuga sinensis based on the analysis of distribution patterns of genera of seed plants in two communities. The above statements provide a theoretic foundation for in situ and ex situ conservation of these two species.

This paper reports a newly naturalized genus Ehrharta Thunb.(Gramineae)in China. The importance of recording exotic plants is emphasized. The necessity of legislation for biological safety in China has been briefly discussed in the present paper.

On the basis of field investigation and specimen observation, and information of SEM leaf epidermal micromorphology, the taxonomic revision of Cotoneaster microphyllus Wall.ex Lindl.was carried out. As a result, fifteen specific names belonging to three series(Series Procumbens Klotz;Series Alpigeni和Series Marginati Klotz),are reduced to be synonyms of C.microphyllus Wall. ex Lindl.

Saxifragapseudoparvula H. Chuang, sp. nov.Species similis S. parvulae Engl. et Irmsch., sed plantis gracillimis, 3 - 6 cm altis; petiolis valde longioribus quam laminis; floribus minoribus erectis, petalis valde longioribus quam sepalis,sepalis 1 - 1.5 mm longis, petalis 1.5 -2 mm longis differt.……

Rosaceae is one of the five largest families of Yunnan flora, consisting of 41 genera and 456 species. The total species mumber is slightly less than those of Compositae, Graminae, Orchidaceae, and Papilionaceae in Yunnan.The percentage of genera and species numbers is 74.5% and 52.2% of the total number in the rosaceous flora in China respectively.