In order to explore the karyotype characteristics and evolutionary relationship of different populations of Sophora alopecuroides， the karyotype characteristics and evolutionary of six natural geographic populations distributed in Inner Mongolia， Gansu， Ningxia were analyzed respectively， and chromosome conventional slicing technology was used. The results showed that the number of chromosomes in six populations of S. alopecuroides was constant，2n=2x=36. There were two types of central centromere（m） chromosome and sub-central centromere（sm） chromosome in three populations. Chromosomes of most populations were only central centromere chromosome except for Population 3 in Wuwei， Gansu， with central centromere and sub-central centromere chromosome. The average arm ratio of chromosomes ranged from 1.19 to 1.37， the length ratio was between 1.72 and 2.19， and the karyotype asymmetry coefficient was from 54.30% to 57.17%. There were three types of karyotypes including 1A， 3A and 2B for S. alopecuroides. The karyotype asymmetry coefficient of population 3 of S. alopecuroides was the largest and the evolutionary degree was the highest， while those of population 19（Ordos， Inner Mongolia） was the smallest and the lowest. Cluster analysis showed that the six populations of S. alopecuroides were aggregated into two major branches of A and B. Branch A could be divided into two subclades of C and D. Among them， population 5（Wuwei， Gansu） and population 13（Alxa， Inner Mongolia） were clustered into subclade C， which had the closest relationship， whereas population 3 was clustered into subclade D alone， which was relatively distant with two populations from subclade C. Similarly， branch B could be further divided into subclade E and subclade F respectively. Subclade E was consisted of population 19 and population 43（Ordos， Inner Mongolia）， which had the closer relationship， while Subclade F only contained population 17（Yinchuan， Ningxia）， which had the relatively distant with two populations from subclade E. In this study， the chromosome number， karyotype characteristics and evolutionary trend of S. alopecuroides were discussed at the population level， which provided cytological evidence for further studying the system and evolution， and genetic diversity of germplasm resources of S. alopecuroides.
To clarify the codon usage pattern and phylogenetic relationship of the chloroplast genome between Ranunculaceae and Paeoniaceae， 33 species of Ranunculaceae and seven species of Paeoniaceae were used as materials， and the analysis software CodonW， online software CUSP， and R software were used to analyze the codon characteristics of chloroplast genes， while the MAFFT software， MEGA software were used for phylogenetic analysis respectively. The results showed that the chloroplast genomes of Paeoniaceae and Ranunculaceae （except Columbine） had a high consistency of high frequency codons， with 29 high frequency codons， which were basically biased towards ending with A/U， but the optimal codon were different. The codon bias of the chloroplast genome of Ranunculaceae and Paeoniaceae was mainly influenced by natural selection， and the codon bias of the chloroplast genome of Paeoniaceae was more affected by natural selection than that of Ranunculaceae. The phylogenetic relationship based on the complete chloroplast genome sequence and the CDS sequence of the chloroplast genome showed that although the phylogenetic relationship based on the complete chloroplast genome sequence and the chloroplast genome CDS sequence of Paeoniaceae was different， they could be divided into the peony group and the peony group. The phylogenetic relationship of Ranunculaceae based on the entire chloroplast genome sequence did not conform to the classification relationship of Chinese flora， but it supported the division of Ranunculaceae into four subfamilies and 14 families. The analysis results supported that Paeoniaceae were independent from Ranunculaceae and Ranunculus， and were classified into Saxifraga.
The perennial fern Pteris vittata（Pteridaceae） is a hyperaccumulator of arsenic and is used for remediation of soils contaminated by heavy metals. In order to identify the characters that the P.vittata sporophyte thrives in xeromorphic rocky environments and hyperaccumulates ions， the brightfield and epifluorescence microscopy were used to investigate the anatomical structures and histochemical features of this species. The results were as follows： （1）The structure of the rhizome， adventitious roots and leaves of P. vittata sporophytes were all primary structures， the adventitious roots had an vascular bundles， endodermis with Casparian band， lignified sclerenchyma layers， cortex， rhizodermis. （2）The rhizomes had a dictyostele， endodermis， cortex， epidermis， cuticle. （3）The stipes had a single vascular bundle with a central endodermis， cortex， sclerenchyma layers， while the epidermis had a cuticle. The pinnae had bifacial mesophyll with palisade tissue and spongy tissue， the epidermis had a cuticle. （4）The surfaces of the rhizodermis and the root hairs were pectin-rich and underlain by a lignified cortex， and permeability tests using a berberine tracer showed that these structures retained large volumes of berberine. In summary， the suberized endodermis， lignified sclerenchyma layers， bifacial mesophyll， and a cuticle， all of which reflect an adaption to xeromorphic rocky environments. The result of the berberine permeability test are consistent with the hyperaccumulation of ions by P. vittata.
Leaf anatomical structures of seven Sorbus species at Longcanggou National Forest Park in Sichuan Province were observed by paraffin section method， and the relationship between leaf anatomical structure and environment was discussed in this study. The results showed that： the leaves of seven species were all of typical dorsal-ventral pattern； leaf thickness ranged from 108.16-208.21 μm， significant differences（P<0.01） were observed in the studied species； upper epidermis thickness was greater than the lower， furthermore， papillae were observed in the lower epidermis of pinnate-leaved species； palisade parenchyma was composed of 1-2 layers of cells， the ratio of palisade parenchyma to spongy parenchyma in thickness of S. prattii var. aestivalis was 1.93， and the rest of six species were less than 1 respectively； the vascular bundles of the midrib were all heart-shaped， which were typical collateral vascular bundle； the differences of midrib protuberant degree among species were extremly significant（P<0.01）. Among the anatomical structures， the plasticity of the upper and lower epidermis was the largest， which had strong potential adaptability in the habitat； the midrib had the least plasticity and the overall structure was relatively stable. Palisade parenchyma， spongy parenchyma and midrib were the most different anatomical structures among the seven species. Correlation analysis between leaf anatomical structures and environmental variables indicated that palisade parenchyma thickness， the ratio of palisade parenchyma to spongy parenchyma and cell tense ratio were positively correlated with annual precipitation， precipitation of warmest quarter and altitude（P<0.05）， and were negatively correlated with temperature seasonality（P<0.05）； diameter and protuberant degree of midrib were positively correlated with seasonal temperature（P<0.01）， and were negatively correlated with annual precipitation， precipitation of warmest quarter and altitude（P<0.05）. The adaptability of leaf anatomical characteristics reflect the survival strategies of seven Sorbus species at Longcanggou National Forest Park.
According to Article 9.2 in the International Code of Nomenclature for algae， fungi， and plants（Shenzhen Code）， the typographical errors in the protologues of twenty-five taxa（ferns） in China were corrected respectively， including Gleichenia cantonensis Ching， Hicriopteris omeiensis Ching & P.S. Chiu， Hypolepis yunnanensis Ching， Coniogramme latibasis Ching ex K.H. Shing， Athyrium costulalisorum Ching， Athyrium exindusiatum Ching， Athyrium gongshanense Ching， Athyrium habaense Ching， Athyrium pseudoepirachis Ching， Athyrium submacrocarpum Ching & S.K. Wu， Lunathyrium sichuanense Z.R. Wang var. jinfoshanense Z.R. Wang， Pseudocystopteris remota Ching， Diacalpe medogensis R.C. Ching & S.K. Wu， Arachniodes falcata Ching， Cyrtogonellum caducum Ching， Cyrtogonellum salicifolium Ching & Y.T. Hsieh， Cyrtomium moupingense Ching & K.H. Shing ex K.H. Shing， Cyrtomium tsinglingense Ching & K.H. Shing ex K.H. Shing， Dryopteris grandiosa Ching & P.C. Chiu， Dryopteris occidental-zhejiangensis Ching & P.C. Chiu， Dryopteris subtenuicula Ching & P.C. Chiu， Hemigramma distinctipetiolata Ching， Trogostolon yunnanensis Ching， Colysis liouii Ching and Lepisorus pseudonudus Ching.
Based on the survey of orchid resources in the lower Yarlung Zangbo River region， the priority protection value of each endangered plant was quantitatively calculated using multiple evaluation indexes to determine the endangerment level and priority protection sequence of rare and endangered orchids in the region by combining data collection and specimen review. The endangerment level of 156 species of endangered orchids in 60 genera in the lower Yarlung Zangbo River region was evaluated， among which 15 species were in critically endangered（CR） status， 46 species in endangered（EN） status， 78 species in vulnerable（VU） status and 17 species in near threatened（NT） status； the priority protection range value was 0.853 9-0.416 8， among which 45 species were classified as Class Ⅰ protected plants， 72 species as Class Ⅱ protected plants， and 39 species as Class Ⅲ protected plants.The results of this study differ greatly from the endangered degree and priority protection level of various protected plant lists， and most of the orchids are under enhanced threat in this region， which is consistent with the real survival status of these orchids in the lower Yarlung Zangbo River area， and the protection of orchids in this region is urgent and should be given sufficient attention.
In order to better understand the origin of plant， phylogenetic differentiation and evolution process of flora， to promote the protection of endemic plants， endemic flora regions in Northeast China were systematically investigated respectively， including the species composition， family structure and genus structure， life-form composition， flora characteristics and geographical distribution. The results showed that：①There were 289 species of Chinese endemic plants， 109 species of endemic plants of Northeast China， 154 species of endemic plants of Changbai flora region， 16 species of endemic plants of Daxing’anling flora region， 10 species of endemic plants of Mongolia steppe flora region and 20 species of endemic plants of Northern China flora region. ②Among all kinds of endemic plants， herb were the most， and perennial herbs were the most dominant， while trees， shrubs and vines were the less. ③Chinese endemic plants were densely distributed in Daxing’anling Mountains and Changbai Mountains. ④The concentrated distribution areas of endemic plants of Northeast China were distributed along the main mountains in Northeast China， indicated that the endemic plants of Northeast China mainly originated from mountains. ⑤Changbai flora region had high level of endemism， showed the mature nature of the flora. Daxing’anling flora region， Mongolia steppe flora region and Northern China flora region had low level of endemism， showed the young nature of the flora. ⑥Endemic plants of Changbai flora region were densely distributed in Changbai Mountains. The endemic plants of Daxing’anling flora region were evenly distributed， and the endemic plants of Mongolia steppe flora region and the endemic plants of Northern China flora region were scattered.
To reveal whether the testa and endosperm are main factors restricting the seed germination of Sinopodophyllum hexandrum， anatomical structure of seed in different germination stages（1， 7， 14， 21 and 28 d） of S. hexandrum were observed by using the tissue sectioning microscopy， and morphological characteristics of plants were investigated after the germination seeds sowing 7-210 d. The seed of S. hexandrum was composed of testa， endosperm and embryo. The testa contained episperm and endopleura， the episperm was compact and regular and it was composed of palisade cells and epidermal cells from outside to inside， and the endopleura was composed of 5-6 layers sponge cells. The endosperm accounted for most of the seed， included micropylar endosperm and outer endosperm. The embryo consisted of radicle， hypocotyl and cotyledons， surrounded by the compacted testa， multilayer-micropylar endosperm and outer endosperm. During the germination stage， the radicle and hypocotyl began to elongate from 1-7 d， two cotyledons separated from 7-14 d， the radicle broke through the micropylar endosperm and testa from 14-21 d， the radicle， hypocotyl and cotyledons continued to expand and elongate from 21-28 d. 3 function leaves and 5 adventitious roots were formed on average after seeding for 210 d. The compacted testa（physical dormancy） and multilayer endosperm（mechanical dormancy） were the two main factors that restricted seed germination of S. hexandrum.
Being the key floral structure of the reciprocal relationship between flowering plants and pollinators， the analysis of the differences of nectary structure among species with different reproductive characteristics could provide theoretical basis for understanding the evolution of reproductive characteristics of flowering plants. Two contrary species， Roscoea cautleoides with highly specialized outcrossing pollination system and R.schneideriana with autonomous selfing， were used to explore the biological importance of nectary. Nectary size and volume were recorded in the field and nectary location， external form and internal structure were observed by paraffin section staining method. The results showed that： both species had structural nectary. From the external morphology， R. cautleoides nectary was developed and secreted higher concentration sugar， while R. schneideriana nectary was wilting and had no nectar secretion. From the internal structure comparison， R. cautleoides nectary was specialized and the division of structure was clear， while R. schneideriana nectary structure appeared a degree of degradation. These results provid an important basis for revealing the differences of floral characteristics， pollination mechanism and breeding system， as well as the mechanism of nectar secretion between outcrossing and selfing species in Roscoea. It also lays a scientific foundation for further exploring the coevolutionary relationship between plants and pollinators， and understanding the origin and maintenance mechanism of nectary diversity.
To improve the characteristics of the spore，elater and oil body of Lophoziaceae and to provide detailed information for classification，the morphology of 11 species of the Lophoziaceae was observed by scanning electron microscopy， 6 species provided for the morphological characteristics of spore and elater，and 9 species provided for oil body. The results showed that：①The spores of 6 species of Lophoziaceae were spherical， near spherical or elliptical with brown， reddish-brown or yellowish brown respectively. The spore size of them were from 10-16 μm belonging to MI type，and their faces near pole were usually concave. The ornamentation of the above spores were verrucose，clavate，spinate，granular or short baculite respectively. ②The elaters of 6 species of Lopholoziaceae were densely bispiral with obtuse both ends，and their cuticle were smooth or granulate.③The oil bodies of 9 species of Lophoziaceae were spherical，elliptical or oval，with the diameter between 3-10 μm. The detailed description and illustration on morphological evidence of spores，elaters and oil bodies of 11 species of Lophoziaceae might provide the elemental data for the systematic taxonomy and evolution of Lophoziaceae.
The cuticle is an impermeable fatty layer on the surface of the epidermal cell wall， and closely combined with epidermal cells， the micromorphological characteristics such as the morphology and arrangement of plant epidermal cells， as well as the morphological structure of the stomatal apparatus， can be reflected in the cuticle. In this paper， the cuticular micromorphology of needles of 12 species of Pinus was observed and compared by optical microscope and scanning electron microscope， and 20 characters were described in detail， of which 12 characters came from the inner surface of the cuticles and eight characters from the outer surface of the cuticles respectively. The results showed that these characters had taxonomic importance for the intra-genus classification and the identification of similar species： ①Micromorphological features of the cuticle such as the length of epidermal cells， the length of bristle， the undulating degree of the outer surface of the cuticle， the outline of epidermal cells， the presence or absence of stomatal plug and needle-like substances had their specificities， which could be used as a basis for the classification of Pinus at the section level. The micromorphological features of cuticles did not support the view of merging P. Section Cembra and P. Section Parrya into P. Section Quinquefolius， nor did it support the view of dividing P. Section Pinus into P. Section Pinus and P. Section Trifolius. ②The cuticle micromorphological characteristics of the needles of P. bungeana were partly the same as P. Section Cembra， partly similar to P. Section Pinus， and partly different from other species of Pinus， which could provide a new argument for the establishment of P. Subgenus Parrya. ③Under scanning electron microscope， the anticlinal wall pattern of epidermal cells， the existence or nonexistence of stomatal plug and the stomatal shape of the outer surface could provide interspecific delimitation basis for morphologically similar species of P. taeda and P. elliottii.
In order to reveal the distribution pattern of genetic variation and haplotype geographical distribution pattern of Allium macrostemon， and to infer the refugia in the quaternary glaciation， the chloroplast gene fragments（psbA-trnH， rps16 and trnL-F） and nuclear gene fragments（ITS） of A. macrostemon in 14 regions of China were analyzed respectively. The results showed that the genetic diversity of A. macrostemon chloroplast gene（cpDNA） was lower than that of nuclear gene（nrDNA） （cpDNA：HT=0.868； nrDNA：HT=0.890）. The AMOVA analysis of cpDNA and nrDNA showed that the genetic variations occurred mainly among populations （cpDNA：92.84%； nrDNA：98.40%）， there was significant genetic differentiation among populations（cpDNA：Nst=0.918，Gst=0.866，Fst=0.928；nrDNA：Nst=0.984，Gst=0.855，Fst=0.984）， and had an obvious phylogeographical structure in A. macrostemon populations（Nst>Gst）. A total of 11 chloroplast and 14 nuclear haplotypes were identified in the A. macrostemon populations. The haplotype network and geographical distribution map showed that the chloroplast haplotype H3 and nuclear DNA genotype H1 had the highest frequency and were located in the center of the network structure， which might be the ancient haplotype. In addition， the glacial refuge hypothesis suggested that the region with high genetic diversity， ancient haplotype and more endemic haplotype might be the glacial refugia of A. macrostemon. Therefore， it was speculated that in the quaternary glaciation， A. macrostemon might be multiple glacial refuges in Dapanshan， Tianshui and Tonghua. The analysis could provide references for the evolution of similar herbs and enrich our understanding of the molecular phylogeography of herbaceous plants in East Asia.
Saxifraga sect. Ciliatae Haworth belonging to Saxifraga Tourn. ex L. has highly species richness， but phylogenetic relationships within the section have not been well resolved. S. subsect. Hirculoideae Engl. is the largest subsection in sect. Ciliatae， which is mainly distributed in the Qinghai-Tibet Plateau and its surrounding areas. Based on the morphological characteristics， the subsect. of Hirculoideae was divided into three complex group， and the species attaching to the bumped vein at the leaf submarginal was classified to the S. diversifolia complex. Based on specimen inspection， the morphological and distributional data of 657 specimens from 24 species and two varieties were obtained， and 24 morphological characteristics of each specimen were used for principal component analysis and cluster analysis respectively. A total of 443 geographical distribution records was used to construct the distribution pattern of complex group. The cumulative contribution rate of the first seven principal components with an eigenvalues greater than one was low， only 67.748%. Among the characters of ‘cauline leaves petiolate’， ‘proximal median cauline leaves shape’， ‘inflorescence’， ‘proximal median cauline leaves size’， ‘sepal veins confluent at apex’， and ‘base of leaves cordate’， the contribution value of the first three principal components was large 0.6， could be used as the key characters for classification and identification of S. diversifolia complex. Based on morphological clustering and geographical distribution patterns， S. diversifolia complex could be divided into three branches： Himalayan Branch， Mountains Around Sichuan Basin Branch and Hengduan Mountains Branch（Contained a widespread species： S. egregia）， and the result was also supported by PCA.
Xanthopappus subacaulis is an endemic medicinal plant growing in the alpine meadow of the Qinghai-Tibet Plateau（QTP）. To explore the influence of Quaternary climatic oscillations on the population genetic structure and distribution pattern of X. subacaulis， 3 chloroplast DNA fragments（psbA-trnH， rbcL and psbI-psbK） from 123 individuals of 20 populations were sequenced and analyzed respectively in the present study. The results showed that 6 haplotypes were detected in X. subacaulis， among which H1 was an ancient haplotype. All populations of X. subacaulis had haplotype H1 except for P7. H3， H5 and H6 were private haplotypes， among which H3 was a private haplotype of population P7， and H5 and H6 only existed in P18. H2 and H4 were mainly distributed in the population of Qinghai Lake basin. The total genetic diversity（He） and nucleotide diversity（π） were 3.101 and 0.008 903， respectively. The genetic variation among populations（68.98%） was higher than that within populations（31.02%）， and the genetic differentiation among populations was relatively higher（FST=0.689 85，P<0.01）. The genetic differentiation coefficient NST of populations（0.727） was higher than that of GST（0.656）（P>0.05）， which indicated that there was no obvious phylogeographical structure in the sampling regions. The results of mismatch distributions and neutrality tests revealed that the population of X. subacaulis might have experienced recent expansion. Therefore， the study suggests there are micro-sanctuaries in Qinghai Lake basin of Qinghai Province and Lintan region of Gansu Province during the Quaternary glaciations， and suggests that the Quaternary climate change and QTP uplift shape the modern geographical distribution pattern of X. subacaulis.
Improving reproductive ability of invasive plants might be an important mechanism for successful invasion， but there might be different in variation of reproductive organ traits among the different habitats， especially in the trade-off relationship. The plant Plantago virginica was taken as material， the inflorescences in three habitats including lawn， wasteland and understory， were collected to investigate the differences of morphology， biomass， and the allometric relationship of spikelet and peduncle among different habitats. The results showed that， there were significant differences in most inflorescence morphological and biomass indexes of P. virginica in different habitats. The inflorescences of P. virginica in lawn and wasteland habitats were slender， while that in understory habitat was short and strong. The allometric relationships among different traits of reproductive organs of P. virginica were both conservative and variable， showing different environmental sensitivities. The size dependence of reproductive resource allocation of P. virginica in different habitats was also inconsistent. Therefore， the inflorescence traits and resource allocation of P. virginica in different habitats are both plastic and relatively conservative， which might be an important manifestation of its high invasive ability.
Ceratopteris thalictroides L. Brongn. was treated with different concentrations of brefeldin A（BFA） for 10， 20， 30 h， respectively and the resin sections were observed by optical microscope and electron microscope. On this basis， the periodic acid schiff reaction（PAS） and Sudan black B reaction were carried out. The results showed that in the control， the egg of C. thalictroides in the middle stage of development was larger， the nucleolus was round， and the organelles such as Golgi body and endoplasmic reticulum were complete. The fertilization pore between egg and ventral canal cell was clearly visible and there was only a small amount of vesicular secretion in separation cavity between them. Egg membrane was thick with distinct layers. However， under the treatments， the fertilization pore and egg membrane were not typical， which were composed of a large number of vesicles with different sizes. There were more mitochondria and a few Golgi body under fertilization pore； membrane organelles such as Golgi body and endoplasmic reticulum， etc. were broken. A large number of osmiophilic vesicles were distributed above nucleus and below egg membrane and the separation cavity was filled with flocculent substances. Tissue localization showed that separation cavity of the control was empty， while those of treatments were full of polysaccharides. In conclusion， BFA could damage membrane organelles such as endoplasmic reticulum and Golgi body， etc.， affected the normal function of secretory system first and then the formation of egg membrane and fertilization pore. The results of this study lay a foundation for further study on the mechanism of fertilization pore formation and the reproductive biology of ferns.
In order to rationally protect and explore the wild poisonous plant resources in the Namjagbarwa region， the distribution of families and genera， the composition of life forms， the toxicity， poisonous parts and toxicological effects of plants were analyzed by field investigation， specimen investigation and related literature books inspection. The results showed that there were 77 families， 167 genera and 242 species of wild poisonous plants in the Namjagbarwa region， among which the dominant families mainly included Araceae， Ranunculaceae， Ericaceae， Fabaceae and Asteraceae respectively. The most poisonous plants with herbaceous life form were 138 species in total. Most of the plant toxic parts were poisonous whole grass， a total of 109 species. There were 184 species with mild poisonous plants， including 50 minor toxic plants， there were only five kinds of highly poisonous and three kinds of strong poisonous. There were 19 poisonous nectar source plants， Scrophulariaceae and Ranunculaceae were dominant； in terms of toxicology， most of them were nervous system poisoning. There were many kinds of poisonous plant resources in the Namjagbarwa region， but there was less use of these resources. It was necessary to strengthen the understanding and protection of poisonous plants， and carry out rational development and explroation.
Inflorescence is a key character affecting plant reproduction and plays an important role in plant taxonomy and phylogeny. The inflorescence types of Discorea nipponica are diverse， but relevant data are few available and often controversial. In order to distinguish the inflorescence types and characteristics of D. nipponica， a morphological observation combined with paraffin sectioning techniques was carried out to investigate the morphological characters， quantitative characters and development process of inflorescences of D. nipponica respectively. The results showed that the female inflorescence was an axillary spike， and had vestigial anther and pollen sac but didn’t produce pollen. The male inflorescence of D. nipponica showed different characteristics from the description of existing data. The male inflorescence was an infinite one composed of scorpion-tailed monochasium， which belonged to the mixed inflorescence with axillary or terminal buds developed， was shaped like spike. The leaves on some lateral branches of male plants degenerated， and axillary inflorescences gradually shortened towards the tip， presenting conical type with the terminal inflorescence. Male inflorescences had higher values than female ones in terms of average length， the number of florets， the density of florets， and flowering time respectively. The study showed that the male and female inflorescences of D. nipponica morphologies were consistent with the evolution from finite to infinite， exhibited relatively primitive features， which ensured the success of pollination and adaptability to the environment.
Akebia trifoliata belongs to Akebia of the Lardizabalaceae family， and it is a dioecious， monoecious woody vine， with economic value for medicine and food. In order to understand the sexual reproduction process of A. trifoliate， analyze the reproductive reasons of the low seed setting rate of this species under natural conditions， and provide a theoretical basis for its hybrid breeding and new variety cultivation，the embryological characteristics of mega-and microsporogenesis and female and male gametophyte development of A. trifoliate were observed by paraffin section technology. The main results showed that A. trifoliata had six stamens with four locules in each， and the anther wall was fully differentiated， and it was composed of epidermis（1 layer）， endothecium（1 layer）， middle layers（2-3 layer） and tapetum（1 layer） from outside to inside， tapetum belonged to glandular type respectively. The cytokinesis of the microspore mother cell in meiosis was of simultaneous type， and the tetrads were arranged in a tetredraltah， mature pollen grain was two-celled. There were little pollen abortion， and abortion occurred at the microspore tetrad stage. The ovary was one locular， parietal placentation， ovules were hemianatropous， bitegminous and crassinucellate. Its megaspore was of monosporogenesis type， and tetrads were linearly arranged. The chalazal end megaspore developed into functional megaspores， which underwent three times consecutive mitosis and further developed into polygonum embryo sac with seven cells and eight nucleus，another three megaspores degenerated. The early development of the stamens in the female flowers was normal， but the microspores did not develop further until the uninucleate pollen grain stage， the tapetum was not completely degraded， and the anther wall did not crack， the degeneration of the carpel of the male flowers was due to the early lack of development，the carpels heal incompletely， and no ovules are produced.The process of the mega-microsporogenesis and development of female and male gametophyte of A. trifoliata were normal， which was not the reason for the low seed setting rate， but may be related to external factors affecting pollination.
Brachytheciaceae is one of the most diverse and problematic taxonomic families in pleurocarpous mosses. In this paper， the morphology of pseudoparaphyllia of 594 specimens in Brachytheciaceae， which belonged to 19 genera and 44 species， were studied. Results were as follows： ①In Brachytheciaceae， pseudoparaphyllia was triangular to semicircular foliose. According to its apical characteristics， pseudoparaphyllia could be divided into two types： truncate or obtuse， and acuminate. ②Except for the genus Brachythecium， morphology of pseudoparaphyllia among the different species in the other 18 genera was basically the same. ③Morphology of pseudoparaphyllia had taxonomic significance in the genus level.
