plant sciences EDITORIAL BOARD Editor in Chief Richard Robinson Science Educator, Tucson, Arizona [email protected] Associate Editors Robert C. Evans Department of Biology, Rutgers University Wendy Mechaber Arizona Research Laboratories, Division of Neurobiology, University of Arizona Robert S. Wallace Department of Botany, Iowa State University EDITORIAL AND PRODUCTION STAFF Diane Sawinski, Senior Editor Gloria Lam, Editor Mark Mikula, Carol Nagel, Olivia Nellums, Melanie Sanders, Wayne Yang, Contributing Editors Michelle DiMercurio, Senior Art Director Rhonda Williams, Buyer Frances Hodgkins, Proofreader Thérèse Shere, Indexer Mark Plaza, Permissions Assistant Macmillan Reference USA Elly Dickason, Publisher Hélène G. Potter, Editor in Chief Brian Kinsey, Senior Editor ii plant sciences V OLUME 1 Ab–Cl Richard Robinson, Editor in Chief Copyright © 2001 by Macmillan Reference USA All rights reserved. No part of this book may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage and retrieval system, without permis- sion in writing from the Publisher. Macmillan Reference USA Gale Group 1633 Broadway 27500 Drake Rd. New York, NY 10019 Farmington Hills, MI 48331-3535 Printed in Canada 1 2 3 4 5 6 7 8 9 10 Library of Congress Cataloging-in-Publication Data Plant sciences / Richard Robinson, editor in chief. p. cm. Includes bibliographical references (p. ). ISBN 0-02-865434–X (hardcover : set) — ISBN 0-02–865430-7 (vol. 1) — ISBN 0-02-865431-5 (vol. 2) — ISBN 0-02-865432-3 (vol. 3) — ISBN 0-02-865433-1 (vol. 4) 1. Botany—Juvenile literature. 2. Plants—Juvenile literature. [1. Botany—Encyclopedias.] I. Robinson, Richard, 1956- QK49.P52 2000 580—dc21 00—046064 Preface Someone once said that if you want to find an alien life form, just go into your backyard and grab the first green thing you see. Although plants evolved on Earth along with the rest of us, they really are about as differ- ent and strange and wonderful a group of creatures as one is likely to find anywhere in the universe. The World of Plants Consider for a minute just how different plants are. They have no mouths, no eyes or ears, no brain, no muscles. They stand still for their en- tire lives, planted in the soil like enormous drinking straws wicking gallon after gallon of water from the earth to the atmosphere. Plants live on little more than water, air, and sunshine and have mastered the trick of trans- muting these simple things into almost everything they (and we) need. In this encyclopedia, readers will find out how plants accomplish this photo- synthetic alchemy and learn about the extraordinary variety of form and function within the plant kingdom. In addition, readers will be able to trace ✶Explore further in Photosynthesis, Light their 450-million-year history and diversification, from the very first prim- Reactions and Evolution itive land plants to the more than 250,000 species living today. of Plants All animals ultimately depend on photosynthesis for their food, and hu- mans are no exception. Over the past ten thousand years, we have cultivated such an intimate relationship with a few species of grains that it is hardly an exaggeration to say, in the words of one scientist, that “humans domes- ticated wheat, and vice versa.” With the help of agriculture, humans were transformed from a nomadic, hunting and gathering species numbering in the low millions, into the most dominant species on the planet, with a pop- ulation that currently exceeds six billion. Agriculture has shaped human cul- ture profoundly, and together the two have reshaped the planet. In this en- cyclopedia, readers can explore the history of agriculture, learn how it is practiced today, both conventionally and organically, and what the impact ✶Explore further in of it and other human activities has been on the land, the atmosphere, and Agriculture, Modern and the other creatures who share the planet with us. Human Impacts Throughout history—even before the development of the modern sci- entific method—humans experimented with plants, finding the ones that provided the best meal, the strongest fiber, or the sweetest wine. Naming a thing is such a basic and powerful way of knowing it that all cultures have created some type of taxonomy for the plants they use. The scientific un- derstanding of plants through experimentation, and the development of ra- v Preface tional classification schemes based on evolution, has a rich history that is explored in detail in this encyclopedia. There are biographies of more than two dozen botanists who shaped our modern understanding, and essays on the history of physiology, ecology, taxonomy, and evolution. Across the spec- ✶Explore further in trum of the botanical sciences, progress has accelerated in the last two Ecology, History of; Biodiversity; and decades, and a range of entries describe the still-changing understanding of Phylogeny evolutionary relationships, genetic control, and biodiversity. With the development of our modern scientific society, a wide range of new careers has opened up for people interested in plant sciences, many of which are described in this encyclopedia. Most of these jobs require a col- lege degree, and the better-paying ones often require advanced training. While all are centered around plants, they draw on skills that range from ✶Explore further in envisioning a landscape in one’s imagination (landscape architect) to solv- Curator of a Botanical Garden and Landscape ing differential equations (an ecological modeler) to budgeting and person- Architect nel management (curator of a botanical garden). Organization of the Material Each of the 280 entries in Plant Sciences has been newly commissioned for this work. Our contributors are drawn from academic and research in- stitutions, industry, and nonprofit organizations throughout North Amer- ica. In many cases, the authors literally “wrote the book” on their subject, and all have brought their expertise to bear in writing authoritative, up-to- date entries that are nonetheless accessible to high school students. Almost every entry is illustrated and there are numerous photos, tables, boxes, and sidebars to enhance understanding. Unfamiliar terms are highlighted and defined in the margin. Most entries are followed by a list of related articles and a short reading list for readers seeking more information. Front and back matter include a geologic timescale, a topic outline that groups entries thematically, and a glossary. Each volume has its own index, and volume 4 contains a cumulative index covering the entire encyclopedia. Acknowledgments and Thanks I wish to thank the many people at Macmillan Reference USA and the Gale Group for their leadership in bringing this work to fruition, and their assiduous attention to the many details that make such a work possible. In particular, thanks to Hélène Potter, Brian Kinsey, Betz Des Chenes, and Diane Sawinski. The editorial board members—Robert Evans, Wendy Mechaber, and Robert Wallace—were outstanding, providing invaluable ex- pertise and extraordinary hard work. Wendy is also my wife, and I wish to thank her for her support and encouragement throughout this project. My own love of plants began with three outstanding biology teachers, Marjorie Holland, James Howell, and Walt Tulecke, and I am in their debt. My many students at the Commonwealth School in Boston were also great teachers— their enthusiastic questions over the years deepened my own understanding and appreciation of the mysteries of the plant world. I hope that a new gen- eration of students can discover some of the excitement and mystery of this world in Plant Sciences. Richard Robinson Editor in Chief vi Geologic Timescale started Era Period Epoch (millions of years ago) Holocene 0.01 Quaternary Pleistocene 1.6 Cenozoic Pliocene 5.3 Neogene 66.4 millions of Miocene 23.7 years ago–present time Oligocene 36.6 Tertiary Paleogene Eocene 57.8 Paleocene 66.4 Late 97.5 Cretaceous Early 144 Mesozoic Late 163 245–66.4 millions of Jurassic Middle 187 years ago Early 208 Late 230 Triassic Middle 240 Early 245 Late 258 Permian Early 286 Pennsylvanian Late 320 Mississippian Early 360 Carboniferous Paleozoic Late 374 570–245 millions of Devonian Middle 387 years ago Early 408 Late 421 Silurian Early 438 Late 458 Ordovician Middle 478 Early 505 Late 523 Cambrian Middle 540 Early 570 Precambrian time 4500 4500–570 millions of years ago vii Contributors Miguel Altieri Richard E. Bir Lynn G. Clark University of California, Berkeley North Carolina State University Iowa State University Sherwin Toshio Amimoto Jane H. Bock W. Dean Cocking Redondo Beach, CA University of Colorado James Madison University Edward F. Anderson Hans Bohnert James T. Colbert Desert Botanical Garden, Phoenix, Nara Institute of Science and Iowa State University AZ Technology Daniel J. Cosgrove Gregory J. Anderson Brian M. Boom Pennsylvania State University University of Connecticut New York Botanical Garden Barbara Crandall-Stotler Mary Anne Andrei David E. Boufford Southern Illinois University Harvard University Herbaria Minneapolis, MN Donald L. Crawford Wendy L. Applequist John L. Bowman University of Idaho Iowa State University University of California, Davis Thomas B. Croat Rebecca Baker James R. Boyle Missouri Botanical Garden Cotati, CA Oregon State University Lawrence J. Crockett Peter S. Bakwin James M. Bradeen Pace University National Oceanic and Atmospheric University of Wisconsin-Madison Sunburst Shell Crockett Administration Irwin M. Brodo Society of American Foresters Jo Ann Banks Canadian Museum of Nature Richard Cronn Purdue University Robert C. Brown Iowa State University Theodore M. Barkley Iowa State University Anne Fernald Cross Botanical Research Institute of Texas Leo P. Bruederle Oklahoma State University Ronald D. Barnett University of Colorado, Denver Rodney Croteau University of Florida Robert Buchsbaum Washington State University Patricia A. Batchelor Massachusetts Audubon Society Judith G. Croxdale Milwaukee Public Museum Stephen C. Bunting University of Wisconsin Hank W.