• Korean Journal of Plant Taxonomy
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• v.44 no.4
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• pp.261-275
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• 2014

Although a few recent taxonomic studies focusing on infraspecific taxa in each species of Isodon have been reported, a detailed taxonomic revision of the Korean Isodon taxa has yet to be performed. We investigated the morphological characters of Korean Isodon based on approximately 600 herbarium sheets from major herbaria in Korea and Japan. We identified characters which distinguish seven Korean Isodon taxa and created a key to Korean Isodon based on the results from this study and on recent studies of the Korean Isodon taxa. The following unique characters for several taxa were recognized: 1) dense non-glandular hairs in stems for I. inflexus var. canescens (over 70 ea/mm on one side of the stem), 2) dense glandular hairs on the abaxial surface of the leaf for I. serra (over $40ea/mm^2$), 3) protruding pistils and stamens from the corolla with the length of the protruding part longer than that of the lower lobe of corolla for I. japonicus, and 4) the presence of non-glandular hairs on the entire surface of the fruit of I. inflexus var. microphyllus. Based on this study, we recognized that there are four species, two varieties, and one forma of Isodon taxa in Korea.