BotGar_Cover (5-8-2004) 11/8/04 11:18 AM Page 1 $19.95/ £14.99 GARDENING & HORTICULTURE/Reference Botany for Gardeners offers a clear explanation of how plants grow. • What happens inside a seed after it is planted? Botany for Gardeners Botany • How are plants structured? • How do plants adapt to their environment? • How is water transported from soil to leaves? • Why are minerals, air, and light important for healthy plant growth? • How do plants reproduce? The answers to these and other questions about complex plant processes, written in everyday language, allow gardeners and horticulturists to understand plants “from the plant’s point of view.” A bestseller since its debut in 1990, Botany for Gardeners has now been expanded and updated, and includes an appendix on plant taxonomy and a comprehensive index. Twodozen new photos and illustrations Botany for Gardeners make this new edition even more attractive than its predecessor. REVISED EDITION Brian Capon received a ph.d. in botany Brian Capon from the University of Chicago and was for thirty years professor of botany at California State University, Los Angeles. He is the author of Plant Survival: Adapting to a Hostile Brian World, also published by Timber Press. Author photo by Dan Terwilliger. Capon For details on other Timber Press books or to receive our catalog, please visit our Web site, www.timberpress.com. In the United States and Canada you may also reach us at 1-800-327-5680, and in the United Kingdom at [email protected]. ISBN 0-88192-655-8 ISBN 0-88192-655-8 90000 TIMBER PRESS 0 08819 26558 0 9 780881 926552 UPC EAN 001-033_Botany 11/8/04 11:20 AM Page 1 Botany for Gardeners 001-033_Botany 11/8/04 11:21 AM Page 2 001-033_Botany 11/8/04 11:21 AM Page 3 Botany for Gardeners Revised Edition Written and Illustrated by BRIAN CAPON TIMBER PRESS Portland * Cambridge 001-033_Botany 11/8/04 11:21 AM Page 4 Cover photographs by the author. Text copyright © 2005 by Brian Capon Photographs and drawings copyright © 2005 by Brian Capon All rights reserved Published in 2005 by Timber Press, Inc. Timber Press The Haseltine Building 2 Station Road 133 S.W. Second Avenue, Suite 450 Swavesey Portland, Oregon 97204-3527, U.S.A. Cambridge CB4 5QJ, U.K. www.timberpress.com Printed through Colorcraft Ltd., Hong Kong Library of Congress Cataloging-in-Publication Data Capon, Brian. Botany for gardeners / written and illustrated by Brian Capon.-- Rev. ed. p. cm. Includes index. ISBN 0-88192-655-8 (pbk.) -- ISBN 0-88192-655-8 1. Botany. 2. Gardening. I. Title. QK50.C36 2005 580--dc22 2004003695 A catalog record for this book is also available from the British Library. 001-033_Botany 11/8/04 11:21 AM Page 5 CONTENTS Introduction 9 PART I. GROWTH 13 Chapter 1 Cells and Seeds: Basics and Beginnings Cells 16 Cell Walls 18 Wall Structure and Cell Growth 20 Growth Processes 22 Meristems 22 Seed Coats 24 Food-Storage Structures and the Embryo 25 Seed Germination 29 Other Germination Requirements 31 Chapter 2 Roots and Shoots: How Plants Mature Root Systems 34 Root Growth 36 Root Hairs and Branches 37 Primary Growth in Stems 38 Development of a Woody Twig 44 Features of a Woody Twig 45 Leaves 47 5 001-033_Botany 11/8/04 11:21 AM Page 6 6 Contents PART II. ORGANIZATION 53 Chapter 3 Inside Stems Herbaceous Stems 56 Stem Thickening 59 Other Features of Wood 64 Monocot Stems 67 Chapter 4 Inside Roots and Leaves A Root’s Primary Tissues 71 Secondary Growth in Roots 73 Cellular Organization in Leaves 74 Plant Cell Types 79 PART III. ADAPTATION 83 Chapter 5 Adaptations for Protection The Garden Habitat 87 Environmental Modification 88 Limiting Factors 91 Protection in Extreme Environments 92 Protection against Animals 96 Protection by Camouflage 99 Protection by Ants 100 Wound Healing 101 Chemical Protection 103 Mode of Operation of Chemical Protectants 106 Other Methods of Defense 108 Chapter 6 Adaptations to Fulfill Basic Needs Competition between Plants 109 Reaching toward the Sun 110 Spreading Stems 111 Climbing Structures 113 001-033_Botany 11/8/04 11:21 AM Page 7 Contents 7 Lianas and Epiphytes 115 Supportive Roots 115 Special Methods of Water Uptake 117 Adaptations for Water Storage 118 Underground Food- and Water-Storage Organs 120 Saprophytes and Parasites 124 Mycorrhizae and Root Nodules 126 Insectivorous Plants 128 PART IV. FUNCTIONS 131 Chapter 7 Control of Growth and Development Growth Responses to Light 134 Responses to Gravity and Touch 137 Other Growth Movements in Plants 140 Hormones and the Aging Process 141 Control of Branching and Adventitious Root Formation 143 Other Hormone Effects: Synthetic Growth Regulators 144 Environmental Control: Temperature 145 Vernalization 147 Environmental Control: Photoperiod 148 Chapter 8 The Uptake and Use of Water, Minerals, and Light Osmosis: The Cell’s Water Pump 152 Development of Root Pressure 155 Transpirational Pull 156 Cold Hardening 158 Mineral Nutrient Needs 158 Soils 163 The Photosynthetic Apparatus 165 Light Transformed into the Energy in Food 168 The Photosynthetic Process 169 Gas Exchange with the Atmosphere 172 001-033_Botany 11/8/04 11:21 AM Page 8 8 Contents PART V. REPRODUCTION 175 Chapter 9 From Flowers to Fruits Flower Parts and Their Functions 178 Pollination by Animals 182 Road Maps and Rewards 183 Inflorescences 186 Pollination by Wind and Water 189 Pollination Alternatives 191 The Reproductive Process 193 Seedless Fruits and Unusual Embryos 195 Fruit Types 195 Seed Dispersal 198 The Cost of Reproduction 200 Chapter 10 Strategies of Inheritance Genetics: The Science of Heredity 201 Mitosis and Meiosis 202 The Life Cycle of a Moss 203 The Life Cycle of a Fern 205 The Two Generations of Flowering Plants 207 Chromosome Segregation during Meiosis 209 Gene Segregation during Meiosis 210 Consequences of Imperfection 213 The Origins of Polyploidy 214 Custom-made Plants of the Future 217 Epilogue 219 Appendix: Plant Names 220 Glossary 224 Index 234 001-033_Botany 11/8/04 11:21 AM Page 9 INTRODUCTION Earth has been called the green planet, a world clothed in a mantle of vegetation that sustains all other forms of life on this tiny spot in the universe. From simple beginnings, plants evolved first among Earth’s living things and thereby established a fundamental princi- ple of nature: Plants, in one form or another, can exist forever without ani- mals, but animals cannot exist without plants. Plants purify the air by exchanging the oxygen we breathe with carbon dioxide, which is poisonous in too high a concentration. Plants convert the energy of sunlight into foods that sustain all animals and, from the soil, draw minerals such as nitrogen, potassium, calcium, and iron that are essen- tial for our well-being. For creatures large and small, plants provide shade from the sun, refuge from predators, and protection from the ever-chang- ing elements. Since the first cells came into being millions of years ago, plants have been the connecting links in an unbroken chain of life. It is they that have made the biosphere, the part of Earth’s crust where both plants and animals exist, a place of limitless opportunity for human inquiry. The range of uses we make of plants is as broad as our ingenuity permits. We have exploited them for fibers to make cloth, drugs to cure a multitude of ailments, and wood to construct houses, furniture, and ships. From them we have extracted raw materials to manufacture innumerable goods, includ- ing paper. Without that latter commodity, the detailed history of our race would not have been recorded and so remembered, nor could knowledge have been so easily disseminated. And culture, the possession of which makes humans out of animals, would never have developed beyond the basic skills and habits of primitive peoples had we not had paper on which to write music, poetry, and prose. Some of us look at plants as a source of livelihood, while others find them intriguing subjects for scientific study. But most enjoy plants for the sheer delight of having them in their everyday surroundings, to savor the varied colors, textures, tastes, and aromas that they alone can offer. Plants 9 001-033_Botany 11/8/04 11:21 AM Page 10 10 Introduction stimulate the senses, bring us a sense of peace and tranquility, and direct our thoughts to contemplating the mysteries of life. Few gardeners share the botanist’s knowledge of plant biochemistry, anatomy, physiology, and intricate reproductive systems, yet all have expe- rienced the extraordinary satisfaction derived from growing flowers, fruits, vegetables, and trees. When we work with plants, questions about them inevitably come to mind. What takes place inside a seed after we have set it in the ground? How does water travel from soil to treetops? What makes a plant become bushy with repeated pruning? What controls seasonal flowering patterns? How do plants grow, and why is light necessary to make growth happen? Over the centuries, botanists have worked to find answers to these and other problems. Slowly, plants have revealed some of their secrets. Botany is a useful and rewarding study from which, unfortunately, many laypersons are frightened away by the technical jargon that constitutes the language of the science. The reader will encounter a number of scientific words in the following pages. Some are part of the common parlance of gardeners. For want of suitable nontechnical equivalents, others cannot be avoided when writing such a book. Each technical word, whether common or obscure, is explained in the text and glossary, and occasional reference is made to the Greek and Latin roots from which these words have been derived.