Abstract:The vegetative and propagative organs of Cymbidium sinense were studied by paraffin method and observed under scanning elect ron microscope. The results show that leaf surfaces of Cymbidium sin ense are covered with cuticle. The stomata with tetracyclic type are found t o distribute in the abaxial epidermis. The mesophyll is not differentiated into spongy and palisade tissues, but mesophyll near midrib in tip and middle parts o f leaf is often lengthened to appear as palisade-liked tissue. Vascular bundles of leaf with parallel venation are collateral bundles．Vascular boundles in pseudobulb are scattered in ground tissue．In cross section view，from outer to inner part，root includes velamen，cortex，and vascular cylinder．Basic structure of each part of perianth is similar to each other and is composed of epidermis，ground tissue and vascule bundle． Epiderm is of lip and column are glandular epidermis， with a stylar canal in column．Tricarpous pistil has one-locular ovary with parietal placentation．Tetrads have no ornamentation in appearance．A capsule fruit．

Abstract:Pinna venation pattern and pinna anatomy of two species, S tangeria eriopus and Bowenia serrulata, represent atives of the two genera in Stangeriaceae were studied in this paper. The two sp ecies (genera) are similar in stomatal character and in the absence of accessory transfusion tissue, but they are very different in stomatal distribution, pinna venation pattern and pinna marginal shape, presence or absence of mucilage cana l, differentiation of palisade and spongy parenchyma, characteristics of girder parenchyma and epidermal anticlinal wal1． Pinna venation and pinna anatomy of Stangeriaceae are compared with those of Cycadaceae and Zamiaceae． Stevenson's classification (1992) with two subfamilies and the treatment of Stangeriaceae as a transitional evolutionary position between Cycadaceae and Zamiaceae is supposed by present study．

Abstract:RAPDs were used to study the relationships among species in Hibiscus sect. Furcaria. Twenty-five accessions of 7 species we re examined. Sixteen primers of arbitrary sequences were screened from 80 primer s for DNA amplification. A total of 192 bands were generated, of which 149 bands were polymorphic markers. Dendrogram was constructed using Nei's genetic simila rity value and MINTS program. The result showed that 25 accessions were clustere d in 7 clades, H. penduriformis and H. calyphyllus formed a clade,and 15 accessions of H．cannabinus were clustered in two clades，one being the cultivars，and the other，the wild type materials．The rest 4 species formed 4 individual clades．The most parsimonious dendrogram shows that H．radiatus is closely related to H. sabdarifa．The closely related species to the cultivars of H.cannabinus are H．sabdarifa and H．radiatus, whereas H．trionum appears to be highly diverged from all the other taxa．

Abstract:Among 136 somaclones, five mutants of thermo-sensitive gen ic male sterile rice were obtained by somatic cell culture from two male sterile (MS) lines, IR66707A and IR69700A, which are of cytoplasmic type. The mutants w ere sterile during late spring until early autumn, and became fertile in late au tumn (the end of October) in Guangzhou. In midsummer, when the mutants of young panicle developmental stage to pollen formation stage were used for short-day tr eatment (daylength was adjusted to 8 h daily for 30 days)，all the mutants were still sterile whereas the Nongken 58S (contro1) was converted to be fertile．However,when the mutants were treated under low temperature(22±1℃)for 10 or more days,they became fertile，the seed setting percentage being 17.23％-42.1 9％， whereas those under normal condition (high temperature) were still sterile．These results showed that the fertility conversion in mutants was correlated with temperature rather than with day length． If the mutants were used as female parent to cross with normal variety,the plants in F1 were all fertile，while in F₂ were segregated into 3(fertile):1(sterile)，and in testcross F₁ were in the ratio of 1：1． Genetical analysis indicated that the mutants were controlled by a pair recessive genes．In this experiment，we obtained a thermo-sensitive genic MS mutant that derived from cytoplasmic MS.

Abstract:Nineteen taxa of potted seedlings were put on roofdecks at ca 5 m above ground in air-polluted sites (industrial site, IS; and transportati on site, TS) and less-polluted site (control site at Luhu Park, CS) at Guangzhou city to compare the response of the plants to air pollutants. The integrated i ndex of air pollution at the three sites in 2000 were in the order of IS > TS > CS. The content of chlorophyll and Fv/Fm in leaves of all species after growing for one and half year at two air-polluted sites (IS and TS)decreased，whereas the cell membrane leakage rate increased as compared with the control site．Some plants such as Ficus elastica, F. microcarpa, F. microcarpa cv．Golden leaves，Ormosia pinnata，Nerium indicum，Magnolia delavayi，Fagraea ceilanica， Swietenia mahagoni an dMimusops elengi exhibited more resistance to airpollutants than others such as Acmena accuminatissima，Lysidice rhodostegia, Bombax malabaricum and Hibiscus rosa-sinensis．

Abstract:Heptacodium miconioides Rehd. (Caprifoliaceae) i s a monotypic and endangered species endemic to China. Mature leaves of 3-year-o ld seedlings of this species were used to determine the photosynthetic rate, tra nspiration rate and stomatal resistance in response to light intensity and tempe rature. Optimum temperature for net photosynthetic rate was 26-30℃. There was a power equation between dark respiration rate and temperature at 19-40℃, and a linear relationship between transpiration rate (Tr) and temperature．Highest saturated light intensity，apparent quantum yield，and Pmax appeared in the seedlings at 29℃，but they were the contrary at 39℃．Light compensation point and Tr increased obviously and the photoinhibition was enhanced at 39％．High temperature decreased carboxylation eficiency and increased CO₂ compensation point，which led to a significant decrease of photosyn thetic capacity．It is suggested that mild shading culture of H．miconioides seedlings is beneficial to the reduction of leaf temperature and photoinhibition in the summer．

Abstract:Eight species of the dinoflagellate genus Prorocen trum collected in April-May every year during 1998-2000 from Daya Bay, Guangdong, China, are identified and described. They are P. sigmoides, P. micans, P. tries tinum, P. dentatum, P. minimum, P. balticum, P. mexicanum, and an unknown species. All of them can cause red tide except the unknown one. P. minimum and P. mexicanum are susp ected of being toxic.

Abstract:Seedlings of Acacia auriculaeformis, Eucalyptus urophylla, and Schima superba were tr ansplanted in canopy gaps and under secondary broadleaved forest, Pinus m assoniana forest, Acacia auriculaeformis forest, a nd Eucalyptus robusta forest on Nan'ao Island, Guangdong Provin ce. Leaf area index (LAI), transmittance, and seedling height were measured. Res ults indicated that LAI was greater under forests than in gaps, and the transmit tance was much higher in gaps. Both LAI and transmittance changed with the seasons． Seedlings ofthe three species grew fasteringapsthan un derforests．Seedling height of Acacia and Eucalyptus in gaps increased more obviously than that of Schima， showing ecological response of species to canopy gap condition.

Abstract:An investigation of the flora and vegetation was made in li mestone hill with an area of 47.8 km2 in Shimentai Nature Reserve, Yingde County , Guangdong. Eighty-six vascular plant species included in 77 genera and 51 fami lies are distributed here, of which 12 species are endemic to limestone area, viz. ferns, including Hypodematia crenatum, Pyrrosia s imilis, Pteris cretica, and the seed plants, Sapium roundifolium, Sinosideroxylon wightianum, B oniodendron minius, Ptrocetis tatarinowii, Zanthoxylum armatun，etc．The vegetation in the area studied is classified into 6 forest types．i.e. Ptroceltis tatarinowii forest, Zenia insignis forest, Pistacia chinensis forest, Choerospondias axillaris and Ficus microcarpa forest, A lchonea trewioides and Strobilanthes cusia forest, and Sapium roundifolium forest． The protection and restoration measures oflimestone vegetation after disturbance are suggested．

Abstract:Eighteen species from Elatostema and Pellionia (U rt icaceae) are reported as new records in nine provinces in China, viz. Elato stema sinense H. Schroter for Anhui E. cusp idatum Wight and Pellionia heteroloba Weddell for Fujia n; Elatostema stewardii Merrill for Gansu; Pellionia macrophylla W. T. Wang for Guangxi; Elatostema pruni folium W. T. Wang, E. schizocephalum W. T. Wang, Pell ionia retrohispida W. T. Wang, and P. subundulata W. T. Wang for Guizhou; Elatostema ficoides Weddell for Hunan; E. schizocephalum W．T．Wang and E. yangbiense W．T．Wang for Sichuan；E. aliferum W．T．Wang，E. dissectoides W．T．Wang，E． gungshanense W．T．Wang, and E．lihengianum W ．T．Wang for Xizang；E． brachyodontum (Hand.-Mazz．) W．T．Wang, E．ebracteatum W．T．Wang，E．prunifolium W．T．Wang，E．schizocephalum W．T．Wang．and E. strigulosum W．T．Wang for Yunnan．

Abstract:Five compounds have been firstly isolated from Woodwardia j aponica (L. f.) Sm. On the basis of spectral analysis, the structures of these compounds were identified as kaempferol 3-O-á-L-(4-O-acetyl)rhamnopyranos ide-7-O-á-L-rhamnopyranoside (I), kaempferol 3-O-á-L-rhamnopyranoside-7-O-á-L-rhamnopyranoside (II), woodwardinic acid (III), a-sitosterol (IV), daucosterol (V).

Abstract:The composition of the volatile oil from the roots of Peuc edanum praeruptorum Dunn in Fujian province were analyzed by m eans of GC-MS technique, and 38 chemical constituents, 77.97% of total content, were identified. The main components were a-phellandrene(9.52%),á-bisabolol (8 .44%) anda-pinene (5.22%). Besides, some sesquiterpenes and their oxides such a s caryophyllene (2.62%),longifolene(2.36%) and Z-9-pentadecenol (3.72%) were al so important. The antibacterial experiments of the oil were studied on 4 tested strains in vitro， which showed that the oil had a certain an tibacterial activity against Eschedchm coli，Salmonella typhi and Shigella flexneri.

Abstract:This paper reviews the latest studies and application of gene engin eering formedicinal plants on the following aspects: transgenic organ culture, transfer an d expression of model genes, and specific genes mediated by Agrobacterium.

Abstract:Savanna is the largest biome in southern Africa which repre sents 46% of the total area. Most savanna are used for grazing mainly by cattle and goat. This paper reviews the recent researches on savanna in main aspects in cluding eco-physiology, ecosystem assesment, fire, bush encroachment, succession aldynamics, vegetation degradation and restoration, and ecosystem management strategies.