Before Professor Hiroshi Hara and the University of Tokyo began taxonomic research on the Himalayan plants in 1960, botanical information on the Himalayas was incredibly scanty and scattered. After 20 years of study on Himalayan plants, we now have a valuable document on Himalayan plant taxonomy, "An enumeration of flowering plants of Nepal" (3 vols., 1978-81). This is primarily the result of continuous efforts on the part of the late Professor Hara and his associates, and also of botanists in the Department of Medicinal Plants, Kathmandu; the British Museum (Natural History), London; and the University of Tokyo, Tokyo. They have co-operated to compile an up-to-date botanical catalogue showing the diversity of Himalayan plants and the history of botanical research in the region.

The Himalayan flora, particularly of Nepal, can now be said to be fairly well known to botanists, though several taxonomic groups such as Saxifraga, Pedicularis, and Impatiens remain to be revised. However, at present we have little information relating to the internal and cytological features of the Himalayan plants. The studies included in the present volume will be significant in revealing the diversity of the Himalayan flora.

Nepal is an interesting country, as it contains the most varied altitudes in the world, ranging from the tropical Terai region of approximately 150 m in altitude to the world's highest mountains at nearly 9000 m. Such huge differences occur within a range of only 150 km. The vegetation of Nepal is greatly influenced by variation in the environment, which is due to altitudinal diversity. Over the long span of time, the components of vegetation may become diversified in the localized environment, and as a result local endemic flora are produced. Plants growing in altitudea exceeding 4000 m in particular seem to have adapted themselves to a very peculiar environment. The Himalaya region is one of the beat places in which to study speciation at such high altitudes.

This volume is the first in a five-volume comprehensive study of "The Himalayan Plants". It contains 10 articles relating to the Himalayan flora and plants.

We are much indebted to the National Council for Science and Technology, Nepal, for providing us with facilities during our field researches. We wish to express our sincere thanks to Mr. Mitsuo Kawaguchi, former Secretary, Embassy of Japan, Kathmandu; Dr. Mamoru Arai and Dr. Toshiyuki Akiyama, Fermentation Research Laboratories, Sankyo Co. Ltd., Tokyo; Mr. Takashi Miyahara, Executive, Traras Himalayan Tours, Ltd., Tokyo and Kathmandu; Mr. Kazuyuki Takahashi, Director, Kamoshika Sports, Inc., Tokyo; and Mr. Kenji Midorikawa, Tokyo, for their kindness in aiding us in various ways. We are also thankful to the local administrations of Nepal for their help during our field trip.

Our researches were supported by Grants-in-Aid for Overseas Scientific Research, No. 58041022 in 1983, No. 59043020 in 1984, No. 60041018 in 1985 and No. 61043015 in 1986, from the Ministry of Education, Science and Culture, Japan.