Duodichogamy is the rarest form of dichogamy in angiosperms, which is characterized by flowering in the sequence of male→female→male. Disentangling factors promoting duodichogamy require the discovery of more duodichogamous species in angiosperms. However, extremely limited information on duodichogamous species makes it difficult to make general conclusions. Given the inflorescence morphology and flowering characteristics, the Meliaceae family is highly likely to contain duodichogamous species. We selected 48 individuals from 20 populations in Korea and investigated their flower morphology, arrangement of flowers by sexual condition within inflorescences, and flowering phases and duration of male and female flowers of Toona sinensis (Meliaceae) for 5 years (2011–2015) to determine if the species shows duodichogamous flowering. Toona sinensis belonging to Meliaceae possessed functionally unisexual flowers with rudimentary parts of the opposite sex. The floral organs in male were larger than those in female, except for ovary length and width. In dichasium, male flowers were observed on primary or lateral branches, whereas female flowers were borne only on lateral branches. Overall, individuals from six different populations flowered in the male→female→male sequence, thereby male is blooming far longer than female flowers at the level of individual trees (male vs. female = 17–20 days vs. 2–4 days). This is the first study to report a duodichogamously flowering species, T. sinensis, within Meliaceae. Several flowering characteristics observed from T. sinensis may be important clues used to discover additional duodichogamous Meliaceae species. Short flowering period and relatively small number of female flowers, which is analogous to reduced ovule numbers observed in other duodichogamous species, may intensify male–male competition in T. sinensis. This study contributed to narrowing down potential candidates of duodichogamy based on their geographic distributions and flowering time.

Daegwallyeong is a mountain pass at an altitude of 832 m, which has been designated a conservation area because of its essential role in Korea’s forest ecosystem. Simultaneously, this area is considered a suitable place for forest grazing due to the cool temperature during the summer. Some areas have been converted to grassland for livestock feeding, and the scale has continued increasing. Although livestock in a forest area is more ecofriendly than industrialized facilities, it could impact the native ecosystem, especially in terms of the flora and vegetation. We investigated the changes in flora and vegetation of Daegwallyeong before and after the grassland formation. The total number of vascular plant species changed throughout the survey period. It was decreased by thinning and forest floor removal in 2015. However, it bounced back to the original number in 2016, even after grazing. However, there was a dramatic decrease after the second forest floor removal and 3 months of grazing in 2017. The number of flora slightly increased after the fallow of grazing in 2019, but it did not fully recover. Although the number of flora seemed back to normal, the composition of the flora in 2019 was significantly changed from the forest without disturbance in 2014. First, there was the invasion of naturalized plants such as Taraxacum officinale and Barbarea vularis, as well as ecosystem-disturbing flora such as Carex callitrichos var. nana and Rumex acetosa. Second, the coverage of those species expanded after thinning and grazing. Most importantly, we lost five valuable rare species, Anemone koraiensis, Viola diamantiaca, Chionanthus retusus, Scopolia japonica, and Streptopus ovalis, from the area. Additionally, the ground condition of the area was severely damaged, and plants no longer grow in some areas. The survey and analysis of plants in this study showed the adverse effects of forest grazing practices on rare plants in Daegwallyeong. Forest grazing practices should be carefully conducted to preserve vulnerable plant species and a healthy ecosystem.

In the present study was surveyed the flora, vegetation structure, growing environment, and soil characteristics in the wild habitats of Vaccinium oldhamii and offered basic information for habitat conservation and restoration. Most of the wild habitats of V. oldhamii were located at altitudes between 5 and 1095 m with inclinations of 2–33°, Dense populations were found around the climbing routes of the north-facing mountain slopes and dry rocky areas along mountain ridges. Vascular plants identified in the surveyed V. oldhamii habitats (28 quadrats in 12 habitat areas) included 129 taxa (50 families, 94 genera, 115 species, 9 varieties, 2 subspecies and 3 forms), of which woody plants accounted for 31.1%. The flora identified in the habitat areas were classified into four community types: Community I (Pinus densiflora – Quercus mongolica), Community II (Pinus thunbergii), Community III (Pinus rigida), and Community IV (Castanea crenata). The differences among communities within V. oldhamii habitats were more dependent on the occurrence of species with high importance percentages than on the population sizes of the species observed. The soil characteristics of V. oldhamii habitats were as follows: mostly silty loams; well-drained; shallow available-soil depth; high acidity (pH 3.93–5.07, mean = 4.63, lower than mean Korean forest soil pH of 5.5); and mean available phosphate (=9.485 mg/kg, lower than the mean Korean forest soil available phosphate of 26 mg/kg). Mean species diversity, evenness and dominance were calculated as 1.216, 0.954 and 0.046, respectively.

Vaccinium oldhamii Miq. is an edible berry; however, little is known about its seed dormancy-break and germination. Therefore, the aim of this study was to elucidate the seed-dormancy break and germination characteristics of V. oldhamii. The results showed that the length and width of the seeds of V. oldhamii were 2.4588 ± 0.0273 mm and 1.7028 ± 0.0248 mm, respectively, the filled percentage was 49.0 ± 3.0%, and the 1000-seed weight was 0.9453 g. Additionally, water imbibition test showed that the seed weight of V. oldhamii increased by more than 70% after 24 h, indicating the absence of physical dormancy. Embryo length measured at dispersal and just before germination did not differ significantly. There was no significant difference in E:S (Embryo:Seed) ratio in length at the time of seed dispersal (0.6780 ± 0.0258) and before germination (0.7370 ± 0.0469), indicating the absence of morphological dominance. Temperature treatments showed that the germination of the seed was 0, 6.0, 6.0, 20.0, and 0% under 15, 20, 25, 25/15, and 15/6 °C, respectively. However, treatment with 250 ppm of GA₃ increased the germination of the seeds to 22.0, 36.0, 32.0, 40.0, and 1.0%, respectively. Additionally, treatment with 500 ppm of GA₃ increased the germination to 34.6, 40.0, 40.0, 46.0 %, respectively. These results indicated that the seeds of V. oldhamii exhibited Nondeep physiological dormancy (Nondeep PD). Overall, the findings of this study showed that treatment with 500 ppm of GA₃ at 25/15 °C can effectively break the dormancy of V. oldhamii seeds, which could facilitate further research on the species.

The placement of Daphne genkwa has long been controversial, as its intermediate morphological traits blur the boundary between Daphne and Wikstroemia. To address this challenge, we adopted a chemotaxonomic approach, integrating flavonoid contents with ecological indicators, as an independent line of evidence complementing morphology and molecular data. Using UPLC-UV, six flavonoids were quantified from 16 Korean populations representing six taxa. Multivariate analyses clearly distinguished Daphne and Wikstroemia, with D. genkwa and W. ganpi forming closely related but separate clades. Ecological factors such as precipitation and canopy openness significantly affected flavonoid levels, particularly luteolin 7-O-glucoside and yuankanin. However, the diagnostic flavonoid fingerprints remained consistent across habitats. This study demonstrates that integrating chemical and environmental perspectives can strengthen taxonomic frameworks and support both classification and chemotaxonomic evidence in Thymelaeaceae, offering a methodological basis for future comparative studies across related plant families.