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.

The Rhododendron spp. (R. yedoense and R. mucronulatum) at high elevations of Mt. Halla in Jeju Island are the dominant species in the shrubland. Despite the recent damage to their growth due to climate change and the spread of Sasa spp., these species have not yet been studied systematically in Korea. Therefore, the current study aimed to verify the effect of abiotic factors, e.g., temperature and precipitation, and the spread of Sasa spp. as a neighbor species on their growth based on ring-width measurement data. In addition, the death years were dated using the cross-dating method developed in dendrochronology by comparing the individual ring-width time series from dead Rhododendron spp. with the corresponding chronology established using living trees. For the study, disk samples were obtained from 11 and 10 living R. yedoense and R. mucronulatum, respectively, to establish tree-ring time series. To investigate the death years, six disk samples were also collected from each shrub species. The relatively high occurrence of missing or discontinuous rings is a characteristic of shrubs, which makes tree-ring analysis difficult. Through cross-dating, it was verified that the R. mucronulatum and R. yedoense have 4.3% and 5.3% missing and/or discontinuous rings (the total number of missing and/or discontinuous rings/the total number of tree rings), respectively. All dead shrubs were successfully dated based on synchronization of the individual time series with the corresponding chronologies established using the cross-dated time series; nine shrubs died in the 2010s and the other two shrubs in 1996 and 2001, respectively. Most deaths occurred when Sasa quelpaertensis dominantly occupied the study sites. From the analysis of the relationships between the residual chronologies and the bioclimate predictors (BioClim), only R. mucronulatum showed reliable correlations with the Bio5 (maximum temperature of the warmest month) as +0.28 (p < 0.05) and the Bio18 (precipitation of warmest quarter) as −0.33 (p < 0.05). This result means that summer temperature is a limiting factor for the growth of R. mucronulatum. Through this study, it was verified that Rhododendron spp. at high elevations in Korea can be used for research using tree rings.

<i>Leuzea chinensis</i> (S. Moore) Susanna (Asteraceae), a previously unrecorded species in Korea, was found in Yeongdeok-gun, Gyeongsangbuk-do. <i>Symplocos nakaharae</i> (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 <i>Epilobium parviflorum</i> Schreb. (Onagraceae) grew naturally on the islands of Jeollanam-do. Detailed morphological descriptions and geographical distribution of the three taxa are provided.

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, <i>Juncus torreyi</i> 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. <i>Ozophyllum</i> (subgen. <i>Juncus</i>) according to certain morphological characteristics, such as its racemose inflorescence, the absence of floral bracteole, and unitubular leaves with perfect septa. <i>J. torreyi</i> 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, <i>Egeria densa</i> 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. <i>Egeria densa</i> is similar to <i>Hydrilla verticillata</i> (L.f.) Royle, which is native to Korea. However, it is distinguished from <i>H. verticillata</i> 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. <i>Egeria densa</i> is treated as a malignant weed due to its asexual reproduction and rapid growth. Size changes and the number of populations of <i>E. densa</i> must be investigated.