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Naturalized populations of two alien plants were newly found, and we describe their morphological characteristics and habitats with photographs. One is a member of Juncaceae, Juncus torreyi Coville, and was newly found at a pool of a beach in Gangwon-do. This rush is native to North America and belongs to the sect. Ozophyllum (subgen. Juncus) according to certain morphological characteristics, such as its racemose inflorescence, the absence of floral bracteole, and unitubular leaves with perfect septa. J. torreyi is easily distinguishable from Korean rushes by its long rhizomes with swollen nodes and globular head with 25–100 flowers. Its introduction into Japan and Europe was reported, but the ecological risk associated with its over-dispersal is not known. The other alien plant is a submerged plant, Egeria densa Planch. (Hydrocharitaceae), which was found in streams in Gyeongsangbuk-do and ditches in the Busan-si area, both of which being in the watershed of the Nakdong River. Egeria densa is similar to Hydrilla verticillata (L.f.) Royle, which is native to Korea. However, it is distinguished from H. verticillata by its larger flowers and lack of overwintering organs. This alien plant is native to South America and was introduced for aquarium gardening and naturalized around the world. Egeria densa is treated as a malignant weed due to its asexual reproduction and rapid growth. Size changes and the number of populations of E. densa must be investigated.

Leuzea chinensis (S. Moore) Susanna (Asteraceae), a previously unrecorded species in Korea, was found in Yeongdeok-gun, Gyeongsangbuk-do. Symplocos nakaharae (Hayata) Masam. (Symplocaceae), which had been recorded in the literature but whose native habitat was yet to be identified, was found in Geojedo Island, Gyeongsangnam-do. It was confirmed that Epilobium parviflorum Schreb. (Onagraceae) grew naturally on the islands of Jeollanam-do. Detailed morphological descriptions and geographical distribution of the three taxa are provided.

Prunus subg. Cerasus is the most planted street and landscaping tree in South Korea, but it is difficult to identify species according to their macro-morphologies, leading to problems when attempting properly to manage species quantities. The purpose of this study is to understand the current status of plant types and species compositions in Bundang Central Park in Bundang-gu of Seongnam City and to discuss the necessity of the management of landscaping tree planting. In April of 2021, during the cherry blossom season, a total of 5,866 planted cherry trees were investigated within an area of 6 km2 of Bundang-gu in Seongnam City. As a result, 5,744 trees were sorted into eleven taxa, but the remaining 122 trees were not determined due to their complex morphologies. Prunus ×yedoensis Matsum. accounted for the highest proportion (52.1%), followed by P. serrulata Lindl. var. pubescens Nakai and P. jamasakura Siebold ex Koidz. P. ×nudiflora (Koehne) Koidz., a plant native to Jejudo Island, was not found in this survey. In order to help identify cherry trees based on micro-morphologies, an identification key was presented for the eleven taxa planted as major landscaping trees. It is known that cherry trees frequently form interspecific hybrids in nature. In order to prevent a loss of the genetic originality of native species due to hybridization and gene introgression from foreign cherry trees, it is necessary to manage planting species near the habitats of native taxa and track their origins.

Background In 2020, a categorized list of wetland preferences, major habitats, and life forms of 4145 vascular plant taxa occurring in the Korean Peninsula was published by the National Institute of Biological Resources. We analyzed the list and explored the distribution patterns of the five categorized groups according to wetland preference, along with the information on the major habitats and the life forms of the plants belonging to those categories. Results Out of 4145 taxa, we found that 729 wetland plant taxa (18%) occur in Korea: 401 obligate wetland plants and 328 facultative wetland plants. Among the 729 wetland taxa, the majority (73%) was hygrophytes and the remaining 27% was aquatic macrophytes. Furthermore, almost all of the wetland taxa are herbs; so, woody plants are only 4.7%. The 16 carnivorous taxa distributed in Korea were characterized as obligate wetland plants. Conclusions We expect the categorized information would promote understanding of the characteristics of the plant species and would be an important source for understanding, conservation, and restoration of wetland ecosystems.

Epoxy/silica composites were prepared using aminopropyl triethoxysilane (APTES)-modified silica nanoparticles in the sol state. Different sizes of silica particles were synthesized and they were applied into the epoxy/silica composites with different compositions. The mechanical and thermal properties of the composites were investigated and compared with those of pristine epoxy composite. The structure and morphology of the modified silica nanoparticles and epoxy/silica composites were analyzed using field emission scanning electron microscope. The flexural modulus and tensile strength of the epoxy/silica composites were investigated by universal test machine (UTM). Also, glass transition and thermal stability were investigated using thermomechanical analyzer (TMA). Sizes of silica particles in sol state were controlled by using different concentration of the accelerator. The tensile strength of epoxy/silica composites containing 20 wt% of 30 nm silica was found to be 37.98 MPa. In addition, the glass transition temperature (Tg) decreased with increasing silica particle sizes.

Premise The submersed aquatic plant Hydrilla verticillata ("hydrilla") is important ecologically and economically due to its aggressive growth in both indigenous and nonindigenous regions. Substantial morphological variation has been documented in hydrilla, including the existence of monoecious and dioecious "biotypes." Whereas plastid sequence data have been used previously to explore intraspecific diversity, nuclear data have yet to be analyzed in a phylogenetic context. Molecular and morphological analyses were used to evaluate the genetic diversity and phylogenetic relationships of native and introduced populations. Methods Nuclear (internal transcribed spacer-ITS; phytoene desaturase-PDS) and plastid (trnL-F) sequence data were evaluated phylogenetically using likelihood and Bayesian methods. Leaf morphologies were compared among clades that were identified in phylogenetic analyses. Results Data from both ITS and PDS show multiple instances of polymorphic sequences that could be traced to two or more lineages, including both invasive biotypes in the Americas. Leaf morphological data support the distinctness of lineages and provide a metric for distinguishing monoecious and dioecious biotypes in the United States. Conclusions Nuclear molecular data indicate far greater genetic diversity than could be estimated using plastid markers. Substantially divergent copies of nuclear genes, found in multiple populations worldwide, likely result from interlineage hybridization. Invasive monoecious and dioecious hydrilla biotypes in the Americas are genetically distinct, with both biotypes resulting from admixture among Eurasian progenitors. Genetic similarity to populations in India and South Korea, respectively, implicates these as likely origins for the dioecious and monoecious biotypes.

Epoxy is a widely used thermosetting resin that exhibits good mechanical strength, chemical resistance, and dimensional stability. In order to manufacture this resin, isopropyl alcohol (IPA) and excess epichlorohydrin (ECH) are used as a solvent and an indispensable raw material, respectively. However, ECH and IPA form a ternary azeotropic mixture in the presence of water, rendering it difficult to separate the materials with high purity via distillation. Therefore, a hybrid of pervaporation (PV)-coupled distillation was attempted to improve the epoxy manufacturing process. Silica-zirconia composite membranes were prepared by coating the α-Al2O3/SiO2-ZrO2 intermediate layer and the SiO2 separation layer, i.e., dip-coating was performed on the α-Al2O3 support and subsequently applied to the hybrid process. When the pervaporation process of distillate get from the epoxy by-product was applied, H2O selectivity for IPA/ECH was 15–30 and for H2O/aqueous impurities was 8–54, indicating that H2O for H2O/aqueous impurities permeated relatively faster than IPA/ECH. Therefore, pervaporation coupled distillation using an inorganic composite membrane was feasible for the selective removal of H2O/aqueous impurities in epoxy by-product mixture obtained from epoxy manufacturing.

We have investigated the flora of Yeongheungdo Island in Ongjin-gun, Incheon. A total of 13 separate field trips were carried out from March 2012 to October 2013. As a result, 302 taxa including 80 families, 211 genera, 261 species, 6 subspecies, 31 varieties and 4 forms were identified. These include the following: 1 taxon protected under the Act on the Protection and Management of Wildlife, 3 Korean endemic taxa, 8 floristic indicator species including 2 taxa of grade V, 3 of grade II and 3 of grade I, 33 naturalized taxa with the naturalization rate of 10.9% and 1 northern taxon vulnerable to climate change.

Using a mixed culture of megaspores and microspores from I. coreana, we established high frequency sporophyte regeneration system. After 20 days of culturing in MS basal medium, microscopic examination showed significant morphological changes and the microspore released numerous small vesicles into the culture medium. Megaspores also showed dramatic morphological changes during its incubation time in culture. The spore wall was cracked by the expansion of the megaspore (about 2 times increase in diameter). Simultaneously, brown spots were observed on the surface of the megaspores. The frequency of female gametophytes developing from immature megaspores cultured in MS basal liquid medium (pH 7) supplemented with 1 mgl-1 GA3 was 46%. However, these female gametophytes derived from megaspore only culture could not differentiate into sporophytes. The mixed culture of microspores and megaspores resulted in successful sporophyte regeneration. The highest frequency (12.3%) of green sporophyte regeneration from mixed spore culture occurred when the cultures were maintained at 25℃ under cool-white fluorescent light (40 μmol·m-2·s-1) with a 16 h photoperiod. Regenerated sporophytes were transferred to a test tube containing vermiculite and a sand mixture and left there until they had three leaves. After root growth and the fifth leaf had emerged, more than 95% of the regenerated sporophytes were successfully transferred to the soil and grown to mature plants. The sporophyte regeneration system established in this study could be successfully used for the restoration of the endangered aquatic species, I. coreana.

Determination of the minimum population size is an important component for the ex situ conservation of an endangered species. Here, we present the identification of collection strategies that most efficiently captured the genetic diversity of Brasenia schreberi J.F. Gmelin (water-shield) in natural populations from the mainland (MGC) and Jeju Island (JNS) of South Korea, using amplified fragment length polymorphism (AFLP) markers. A total of 313 and 383 polymorphic bands were detected in the MGC and JNS populations, respectively. All of the 140 sampled ramets were distinguishable by the presence of distinct AFLP phenotypes. According to the simulation of the individual sampling by maximization sampling, 25 and 28 individuals captured all of the genetic diversity in the MGC population (mainland of South Korea) and the JNS population (Jeju Island), respectively. The level of genetic diversity of the core collections was similar to the entire collection, indicating that the core collections very well represent the diversity of the entire collection. We therefore suggest a management unit of B. schreberi based on the genetic information for assessing the minimum population size for its ex situ conservation.

We conducted principal component analyses using the thirty two quantitative characteristics ofNajas from South Korea to examine the morphological variation and diagnostic characteristics. As a result ofour investigation and the morphometric analyses, each taxon could be identified using the leaf width, shape ofthe leaf sheath, number of teeth on the leaf margin, number of anther cells, number of areoles in each longi-tudinal row of seeds, and the ratio of the areole width to the length. Dioecious Najas marina was clearly dis-tinguished from the other monoecious taxa (N. graminea, N. gracillima, N. minor, N. oguraensis, and N.orientalis) by the larger size of the stem, the leaf, the flower and the fruit. The monoecious taxa could be iden-tified using vegetative characteristics except for N. minor and N. oguraensis, which were distinct from eachother according to the locule number in the staminate flower. Keyword: Najas, morphometric analyses, PCA (principal component analysis), monoecy, dioecy, loculenumber나자스말속(Najas L.)은 자라풀과(Hydrocharitaceae Juss.)에 속하는 침수성 수생식물로 전 세계에 약 40종이 알려져 있으며(Haynes, 1979; Triest, 1987, 1988; Cook, 1996; Leset al., 2006), 극지방을 제외한 전 세계의 담수에 생육하고드물게 기수에 자라기도 한다(Sculthorpe, 1967). 나자스말속은 성 체계에 따라 자웅이주인 민나자스말아속(subgenusNajas = Eunajas)과 자웅동주인 나자스말아속(subgenusCaulinia)으로 구분된다(Ascherson, 1864; Rendle, 1899). 나자스말속 식물의 생식기관은 다른 피자식물과 비교하여극단적으로 단순화되어 있는데, 수꽃은 한 개의 수술이1-2층의 막질 화피와 포에 둘러싸여 있고, 암꽃은 한 개의암술이 나출되어 있거나 포에 둘러싸여 있다(Poslusznyand Sattler, 1976). Rendle (1899)은 포의 유무에 따라 나자스말아속을 Spathaceae(수꽃과 암꽃이 모두 포로 둘러싸임), Americanae(수꽃만 포로 둘러싸이고, 엽초는 돌출하지 않음), Euvaginatae(수꽃만 포로 둘러싸이고, 엽초는귀모양으로 돌출함), Nudae(수꽃과 암꽃이 모두 나출됨)등 4개 절로 구분한 바 있다. 그러나 포의 유무는 일관성이*Author for correspondence: hkchoi@ajou.ac.kr 결여된 형질로서 절을 나누는 기준으로 타당하지 않은 것

Genetic variation of nuclear ribosomal ITS (nrITS) and chloroplast DNA (cpDNA) regions was investigated in Brasenia schreberi (Cabombaceae) to assess the population structure and to infer the evolutionary relationship among 12 populations distributed in South Korea. The combined sequence of the two regions was aligned to 2,069 bp, of which 28 sites were variable. In total, 20 genotypes were identified from 240 individuals of B. schreberi. Genotype diversity (Gd) and nucleotide diversity (Pi) on Jeju Island (Gd = 0.2511, Pi = 0.00012) were higher than those of the mainland of South Korea (Gd = 0.1358, Pi = 0.00005). The relatively low level of genetic variation of the mainland populations is associated with its higher genetic differentiation (G ST = 0.095 on mainland and 0.039 on Jeju Island) and human activities. Minimum spanning network analysis demonstrated that the investigated populations of B. schreberi were subdivided into two geographical groups: the mainland of South Korea and Jeju Island. In addition, analysis of molecular variation showed that a large proportion (73.55%) of genetic differentiation existed between the two regions. These results strongly suggest the presence of significant barriers to gene flow between regions. Thus, the management unit for B. schreberi should be carefully designed to avoid the potential risk that can results from the admixture of individuals from the mainland and Jeju Island regions.

 Premise of the study: Two marker systems were developed for the molecular identifi cation of three Trapa species based on the length variation of nuclear AP2 and trnL-F chloroplast intergenic spacer region.  Methods and Results: Our marker systems analyzed 118 individuals among 36 populations from three Trapa species. Trapa incisa was found to have a unique genotype from the other two species. Individuals of T. bispinosa were distinguished from T. japonica because the former had only a single AP2 genotype. Moreover, our results suggest a hybrid status of T. japonica in terms of two bands within an individual. One band was specifi c to T. japonica and the other one shared with T. bispinosa .  Conclusions: Our marker system demonstrates that nucleotide sequence variations can serve as a fast, reliable, and reproducible tool for molecular genotyping and examining the natural hybrid of water chestnut species.

We examined the sixteen quantitative characters of Trapa and conducted principal component analysis for T. japonica Flerow and T. bispinosa Roxb. in South Korea. Trapa bispinosa has been recorded as 'Ma-reum (T. japonica Flerow)' in the Korean flora, but this taxon is distinct from T. japonica in terms of width, thickness and upper horns of its nuts. Principal component analysis (PCA) confirms the morphologically distinct status for the two species. We suggest the common name 'Keun-ma-reum' for Trapa bispinosa to the Korean flora.

The genetic relationship and diversity among four Typha taxa in East Asia were evaluated using amplified fragment length polymorphism (AFLP) markers. Three AFLP selective primer combinations generated a total of 707 amplification products, of which 704 (99.6%) were polymorphic. The unweighted pair-group method with arithmetic mean (UPGMA) dendrogram and principal component analysis (PCA) plot confirmed the taxonomic status of four separate species. East Asian Typha taxa separated into two groups: the first with Typha angustifolia and the second with T. orientalis , T. laxmanni , and T. latifolia with a high bootstrap value for UPGMA (93%) and a low first score for PCA (25%). The two clusters corresponded with two sections based on the bracteoles in the female flower: section Bracteolatae and section Ebracteolatae . T. angustifolia showed the highest genetic diversity among the four Typha taxa (percentage of polymorphic loci [ PPL ] = 71%, H o = 0.157), whereas T. latifolia had the lowest genetic diversity ( PPL = 40%, H o = 0.117). Genetic diversity was related to the presence of the gap between male and female inflorescences. A positive correlation between genetic distance and geographic distance was clearly found in the two species with continuous inflorescences ( T. latifolia and T. orientalis ). This positive correlation was not observed in the other species with discontinuous spikes ( T. angustifolia and T. laxmanni ).

Culture conditions were established for high frequency plant regeneration via somatic embryogenesis from cell suspension cultures of Nymphoides coreana. Zygotic embryos formed pale-yellow globular structures and calluses at a frequency of 85.6% when cultured on half-strength Murashige and Skoog (MS) medium supplemented with 0.3 mg l−1 of 2,4-D. However, the frequency of pale-yellow globular structures and white callus formation decreased slightly with an increasing concentration of 2,4-D up to 10 mg l−1 with the frequency rate falling to 16.7%. Cell suspension cultures were established from zygotic embryo-derived calluses using half-strength MS medium supplemented with 0.3 mg l−1 of 2,4-D. Upon plating onto half-strength MS basal medium, over 92.3% of cell aggregates gave rise to numerous somatic embryos and developed into plantlets. Regenerated plantlets were successfully transplanted into potting soil and achieved full growth to an adult plant in a growth chamber. The high frequency plant regeneration system for Nymphoides coreana established in this study will be useful for genetic manipulation and cryopreservation of this species.

On the basis of amplified fragment length polymorphism (AFLP) and nucleotide sequence data from nuclear ribosomal internal transcribed spacer (nrITS) and three chloroplast DNA regions (rbcL, cpITS, and trnS-psbC spacer), we investigated the species delimitation and the evolutionary lineage of Isoetes asiatica from Hokkaido, Japan. The neighbor-joining (NJ) dendrogram based on AFLP markers revealed the well-defined clusters (bootstrap value = 100%) of I. asiatica. Results from the principal component analysis are largely congruent with those obtained in the NJ dendrogram. The maximum parsimony analysis, based on data from nrITS and three chloroplast DNA sequences, supported a monophyly of three species, I. asiatica, Isoetes echinospora, and Isoetes maritima from Hokkaido, Kamchatka, and Alaska regions. The distinct species status of I. asiatica was also well supported in the combined chloroplast DNA phylogeny. Therefore, I. asiatica appear to represent example of gradual speciation due to spatial isolation of ancestral populations followed by genetic divergence. Our results also suggest that I. asiatica is probably not the ancestral diploid of the polyploids occurring in East Asia.

We report Najas orientalis Triest & P. Uotila and N. oguraensis Miki as unrecorded species from the Korean flora. N. orientalis is distinct from other Najas species in having rounded leaf sheaths and raised testa in the cell walls, and in that this species occurs in the southern region of Korea (Gimhae, Gangjin). N. oguraensis is close to N. minor, but is distinct from this species by having larger male flowers and 4-celled anthers. This species is distributed in the southern region of Korea (Changwon, Jangheung). We also give a new Korean common name for N. gracillima (A. Braun ex Engelm.) Magnus, which is widely distributed in South Korea. A taxonomic key to the six species of Najas is given.

Isoetes coreana Chung and Choi is on the list of critically endangered species in South Korea. Using randomly amplified polymorphic DNA (RAPD) markers, we investigated the genetic diversity within and between seven local populations of I. coreana . Ten RAPD primers produced a total of 94 bands, of which 59 (62.8%) were polymorphic. A low level of genetic diversity was recognized within the populations of I. coreana : polymorphic loci ( P ), with values ranging from 3.4% to 33.9%, and a mean value of 15.5% being observed. Analysis of molecular variance (AMOVA) showed that genetic diversity was greater among populations (81.6%) than within populations (19.7%) or among the three regions included in this study (Han River, Youngsan River, and Nakdong River). In addition, a high degree of genetic differentiation ( θ B = 0.742) was detected among the populations. These results indicate that genetic differentiation has occurred very rapidly. However, the rate of gene flow between populations was found to be as low as 0.059, irrespective of the genetic and geographical distances between the populations, which indicates that genetic drift must have played an important role in forming the present populations of I. coreana . Because a reduction of genetic diversity as a result of genetic drift is undesirable, increasing the gene flow between populations of Korean quillwort I. coreana should be considered as a conservation strategy.

Brasenia schreberi J.F. Gmelin is a declared endangered species found in the lakes and ponds of South Korea. For planning its conservation strategy, we examined the genetic diversity within and among six populations, using randomly amplified polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP). Polymorphisms were more frequently detected per loci with AFLP (69.3%) than RAPD (36.8%). High genetic diversity was recognized within populations: polymorphic loci (PPL) values ranged from 36.3% in the CJM population to 74.5% in the GGT population, with a mean value of 47.8% based on AFLP markers. Great genetic differentiation (θB) was detected among the six populations (0.670 on RAPD and 0.196 on AFLP), and we calculated a low rate of gene flow (Nem), i.e., 0.116 on RAPD and 0.977 on AFLP. Furthermore, a Mantel test revealed that no correlation existed between genetic distances and geographical distances among the six local populations, based on RAPD or AFLP markers. These results are attributed to a number of factors, including an insufficient length of time for genetic diversity to be reduced following a natural decline in population size and isolation, adaptation of the genetic system to small population conditions, and a restricted gene flow rate. Based on both its genetic diversity and population structure, we suggest that a strategy for conserving and restoringB. schreberi must focus on maintaining historical processes, such as high levels of outbreeding, while monitoring increased gene flow among populations. This is because a reduction in genetic diversity as a result of genetic drift is undesirable.

We report Vallisneria spinulosa S. Z. Yan (Hydrocharitaceae) as an unrecorded species from the flora of Korea. This aquatic vascular plant occurs in reservoirs, streams, and ditches at Changnyeong, Changwon, and Gimhae which belong to Nakdong river basin. Vallisneria spinulosa is distinguishable from V. natans (Lour.) Hara already known to Korean flora by the presence of turion and hairs at base of stamen, adnation between pistil and staminodia, the number of stamen, and shape of fruit and seed. V. spinulosa is similar to V. desnseserrulata Makino in the viewpoint of distribution (Japan and southern China), but V. spinulosa has three to five epidermal wings on the surface of seed.

An improved protocol for high frequency plant regeneration via somatic embryogenesis from zygotic embryo-derived cell suspension cultures of watershield (Brasenia schreberi) was developed. Zygotic embryos formed pale-yellow globular structures and white friable callus at a frequency of 80% when cultured on half-strength MS medium supplemented with 0.3 mg l−1 2,4-D. However, the frequency of formation of pale-yellow globular structures and white friable callus decreased slightly with increasing concentrations of 2,4-D up to 3 mg l−1, where the frequency reached ~50% of the control. Cell suspension cultures from zygotic embryo-derived white friable callus were established using half-strength MS medium supplemented with 0.3 mg l−1 2,4-D. Upon plating of cell aggregates on half-strength MS basal medium, approximately 8.3% gave rise to somatic embryos and developed into plantlets. However, the frequency of plantlet development from cell aggregates was sharply increased (by up to 55%) when activated charcoal and zeatin were applied. Regenerated plantlets were successfully transplanted to potting soil and grown to normal plants in a growth chamber. The distinctive feature of this study is the establishment of a high frequency plant regeneration system via somatic embryogenesis from zygotic embryo-derived cell suspension cultures of watershield, which has not been previously reported. The protocol for plant regeneration of watershield through somatic embryogenesis could be useful for the mass propagation and transformation of selected elite lines.