Weeds are a fascinating study for specialists, not only because of their economic importance, but also since in this case biology must be combined with history and agriculture (and its economic aspects). Thus, weed scientists may be concerned with pure basic research, concentrating on general aspects, or with applied science, i.e. having a practical orientation. One of the aims of this book is to create a synthesis between these two branches of study and to review the literature of both fields. The agrestals, the weeds of arable land ~ the most important group from an economic point of view ~ was chasen as the main topic. Other weed groups could only be mentioned briefly (e.g. grassland weeds), or superficially (e.g. aquatic weeds), or had to be omitted completely (e.g. ruderals, because they are so heterogeneous), to keep this volume to an acceptable size and price. Nevertheless, nearly all subsections of botanical science have been treated.

We have edited this book in honour ofMakoto Numata, the nestor of Japanese plant ecology, who will celebrate his 65th birthday in November 1982 and will be retiring from office in March 1983. As the main concern of his work during the last years was to educate people in ecological understanding - probably the only possibility for mankind to master the 'environmental problems' - the topic chosen for this book seemed the most suitable one to honour the retiree. We hope that this volume will prove to be useful for many in carrying through this important task of modern ecology. We are grateful to the authors and particularly to Mr. Peters and the staff of Dr. W. Junk publishers for their patient cooperation. We are also indebted to Jan Knaapen for making the index. Wien, Utrecht and Chiba, June 1982 The Editors VII Contents Preface.................................................................................................... VII List of contributors....................................................................................... XI A biography of Makoto Numata by I. Ikusima ........................................................ .

Weeds are a fascinating study for specialists, not only because of their economic importance, but also since in this case biology must be combined with history and agriculture (and its economic aspects). Thus, weed scientists may be concerned with pure basic research, concentrating on general aspects, or with applied science, i.e. having a practical orientation. One of the aims of this book is to create a synthesis between these two branches of study and to review the literature of both fields. The agrestals, the weeds of arable land ~ the most important group from an economic point of view ~ was chasen as the main topic. Other weed groups could only be mentioned briefly (e.g. grassland weeds), or superficially (e.g. aquatic weeds), or had to be omitted completely (e.g. ruderals, because they are so heterogeneous), to keep this volume to an acceptable size and price. Nevertheless, nearly all subsections of botanical science have been treated.