This study was carried out to investigate the flora of Gyodongdo island (Ganghwa-gun). The vascular plants from 11 field surveys were revealed to belong to a total of 629 taxa; 118 families, 364 genera, 561 species, 5 subspecies, 53 varieties, 7 forms and 3 hybrids. 184 taxa were the first records from this region. The plants in Gyodongdo island are composed of the deciduous broad-leaved and conifer-mixed forests which are the common ones in the middle part of the Korean Peninsula. Five taxa of Korean endemic plants such as Clematis brachyura Maxim., Viola seoulensis Nakai, Populus × tomentiglandulosa T. B. Lee, Forsythia koreana (Rehder) Nakai and Hemerocallis hakuunensis Nakai were collected. Endangered wild plants designated by the law called 'Protection Law for Endangered wild fauna and flora' were one taxon. The red list plants according to IUCN valuation basis were examined for 13 taxa; endangered (EN) species of Prunus yedoensis Matsum., Vulnerable (VU) species of both Utricularia pilosa (Makino) Makino and Iris ruthenica var. nana Maxim., Near Threatened (NT) species of Senecio argunensis Turcz., Least Concern (LC) species of Platycladus orientalis (L.) Franco, Potentilla discolor Bunge, Limnophila sessiliflora (Vahl) Blume, Acorus calamus L., Phacelurus latifolius (Steud.) Ohwi, Pseudoraphis ukishiba Ohwi, Belamcanda chinensis (L.) DC., and Not Evaluate (NE) species of both Astragalus sikokianus Nakai and Potamogeton oxyphyllus Miq. The floristic regional indicator plants found in this area were a total of 47 taxa comprising three taxa of gradeⅤ, four taxa of grade Ⅳ, nine taxa of grade Ⅲ, 10 taxa of grade Ⅱ, and 21 taxa of gradeⅠ. The naturalized plants were identified as 62 taxa and the percentage of naturalized index (NI) was 9.9 % and the percentage of urbanization index (UI) was 19.3 %, respectively. Furthermore, hemicryptophytes (28 %), therophytes (26 %), hydrophytes (13 %) and geophyte (12 %) showed high proportional ratio in life form spectrum.

INTRODUCTION
 MATERIALS AND METHODS
  1. Survey Site Information
  2. Survey Method and Analysis
 RESULTS AND DISCUSSION
  1. Species Composition of Vascular Plants
  2. Korean Endemic Plants
  3. Endangered Wild Plants and Red List Plants
  4. Floristic Regional Indicator Plants
  5. Naturalized Plants
  6. Life Form Composition
 REFERENCES

• Jung-Hyun Kim(Plant Resources Division, National Institute of Biological Resource, Incheon 404-708, Korea) Corresponding author
• Sun-Yu Kim(Plant Resources Division, National Institute of Biological Resource, Incheon 404-708, Korea)
• Byoung Yoon Lee(Plant Resources Division, National Institute of Biological Resource, Incheon 404-708, Korea)
• Chang-Young Yoon(Department of Life Science and Biotechnology, Shingyeong University, Hwaseong 445-741, Korea)