The genus Lespedeza is disjunctively distributed in Asia and North America, and consists of about 40 species (Ohashi, Polhill, & Schubert, 1981). Since Maximowicz (1873) this genus has been divided into two sections: sect. Lespedeza and sect. Macro-lespedeza (see p. 92). The section Macrolespedeza is distributed only in East Asia, ranging from the Himalayas to Japan and Siberia through mainland China, Taiwan, and Korea.

In Japan sect. Macrolespedeza is represented by several species and infraspecific taxa. Most grow abundantly on open habitat throughout Japan, and some even extend into thickets. The Japanese species have been studied by many taxonomists, although they have not yet been successfully circumscribed or clearly distinguished from each other due to their lack of significant characters and also to the presence of interspecific hybrids. Since 1979, we have been studying Lespedeza and its allied genera through field surveys in various localities in Japan and Hong Kong (Akiyama & Ohba, 1982, 1983a, b, c, 1985, 1988).

The present paper aims to provide a detailed revision of the species of sect. Macrolespedeza that occur in Japan and neighboring regions. We have discovered significant characters, especially in the flowers, which we think are sufficient to circumscribe the species of sect. Macrolespedeza. These characters were primarily investigated in the wild populations in Japan. In order to clarify the variation and distribution range of each species, herbarium specimens from various herbaria were also examined. In this paper the specific and infraspecific taxa of sect. Macrolespedeza will be revised based on a synthesis of present knowledge.

In the text, the following abbreviations of the herbaria (according to Index Herba-norum, Part 1, Ed. 7 (Holmgren, Keuken, & Schofield, 1981)) are used, except for that with an asterisk.

A: Arnold Arboretum of Harvard University, Cambridge, U.S.A. CAL: Central National Herbarium, Botanical Survey of India, Howrah, India. GH: Gray Herbarium of Harvard University, Cambridge U.S.A. HK: Herbarium, Agricultural and Fisheries Department, Hong Kong. K: The Herbarium Royal Botanic Gardens, Kew, Richmond, England, U.K. KAG: Herbarium, Faculty of Agriculture, Kagoshima University, Kagoshima, Japan. KANA: Herbarium, Faculty of Science, University of Kanazawa, Kanazawa, Japan. KIEL: Botanisches Institut der Universität Kiel, Federal Republic of Germany. KYO: Herbarium, Department of Botany, Faculty of Science, Kyoto University, Kyoto, Japan. L: Rijksherbarium, Leiden, the Netherlands. LE: Herbarium of Department of Higher Plants, V. L. Komarov Botanical Institute of the Academy of Sciences of U.S.S.R., Leningrad, U.S.S.R. MAK: Makino Herbarium, Faculty of Science, Tokyo Metropolitan University, Tokyo, Japan. NA: Herbarium, U.S. National Arboretum, Washington, D.C., U.S.A. SAP: Laboratory of Plant Taxonomy and Ecology, Botanical Institute, Faculty of Agriculture, Hokkaido University, Sapporo, Japan. SHO*: Herbarium, Biological Laboratory, Shoei Junior College, Kobe, Japan. TI: Department of Botany, University Museum, University of Tokyo, Tokyo, Japan. TNS: Department of Botany, National Science Museum, Tokyo, Japan. TOFO : Department of Forest Botany, University Museum, University of Tokyo, Tokyo, Japan. TUSG: Herbarium, Botanical Garden, Faculty of Science, Tohoku University, Sendai, Japan.