Search

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.

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.

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

 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.

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.

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.