Mabian Dafengding National Nature Reserve is located in the limits of Mabian County,Sichuan and on the basis of field investigations and literatures references;the seed plant florae are studied.It is shown that there 1 240 species,446 genera and 120 families of seed plants of which there are 27 species,11 genera and 5 families belonging to gymnosperms,and 1 213 species,435 genera and 115 families belonging to angiosperms.The reserve is composed of diverse floristic elements which mainly consist of ancient floristic elements and Yunnan-Tibet plateau elements.There are 34 families falling into the category of pantropic and making up 40.96%,and the genera have 15 areals mainly composed of tropic floristic elements,which involve 264 genera accounting 64.71% of the genus total.The similarity coefficients reveal that the floristic elements in the reserve are closely related to those in Meigu Dafengding Nature Reserve and the florae of the two reserves are very identical and thus they may have evolved from one same ancient flora.
Leaf epidermis characters in 16 species 1 variety(belonging to all the four sections) of Heracleum(Apiaceae) in SW China were investigated using light microscopy(LM) and scanning electron microscopy(SEM).The stomatal size,density and index were measured,and the statistical t-test method was used to ascertain the significant level of the differences in the stomata of each species.It was shown that the stomata were anomocytic and existed on the abaxial epidermis in all the species examined,and on the adaxial epidermis in a few of species.The length and density of the trichomes vary with the species and presented on abaxial epidermis of most studied species and on the adaxial epidermis of some species.The adaxial epidermis cells were usually irregular or polygonal in shape with anticlinal walls straight,repand,or sinuous,and the epidermal of abaxial epidermis cells were usually irregular in shape with anticlinal walls repand,or sinuous.Under SEM,the inner margin of the outer stomatal rim was nearly smooth,repand or erose,and the cuticular membrane of the leaf epidermis was stripe,covered with granular or squamose wax.The types of outer stomatal rim and wax were reliable characters to identify some species.These data of leaf epidermis of Heracleum demonstrated that there are many distinct characters among the species.We discussed the systematic and evolution significance of leaf epidermis,and a dichotomous key of Heracleum according to leaf epidermis characters was also compiled in this paper.
Based on overall and sample investigation,175 species of resource plants belong to 76 genera were discovered in community Pine koraiensis of Daliangzihe National Forest Park.Through analyzing of composition of genera and different synusia,it shows that:(1) The dominant floristic element is temperate type,(2) proportion of E.Asia N.Amer.Disjuncted type and E.Asia type are relatively high,(3) it is short of genera and species of tropical type,but the character of tropical forest will appear to some extent in the summer.
The micromorphological characteristics of pericarp surface(MFPS) in 18 species of Pleurospermum in China were observed under SEM for the first time.The result shows that MFPS(i.e.the visibility of epicarp cell,the types of ornamentation and epidermal secretion) exhibit rich diversity and certain regularity,which could be evaluated as the significant references for inter-species identification and infrageneric classification.Based on MFPS,the species could be divided into three types,and this conclusion also coincides with the morphological cladistic and molecular phylogenetic result mainly.In hence,our study suggests that the MFPS is an important evidence for the research of classification and infragenetic relationship of Pleurospermum,as well as for the identification of some doubtful species.According to our analyses and previous studies,we suggest that the Himalayan region is both the distribution and diversity center of Pleurospermum.
In this paper,pollen morphology of 6 species of the genus Peucedanum was investigated.Pollen grains of all the species were examined by LM and SEM.Among them 3 species were palynologically reported here for the first time.The study showed that pollen grains of Peucedanum were in various shapes.Their frame work was trigonal in solid form Ktricolporate,pleurot reme and exine 2-lauered.The statification of exine was clear.According to the characteristics of the pollen grains in Peucedanum,it may be divided into clearly distinguished types: Rectangular type and Equatorially-constricted type.The evolutionary trends of pollen types were as follows: retangular type-equatorial-constrictd type.Pollen information supports Peucedanum as an advanced taxon in Umbelliferae.The trendency of evolution in Peucedanum is that:the size of pollen is from big to small;equater is from straight to contractus.According to pollen information,sect.Bracteolata shoud be a comparatively primitive taxon.
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