Plant Systematics An Integrated Approach Third edition Gurcharan Singh University of Delhi Delhi, INDIA CIP data will be provided on request Science Publishers www.scipub.net 234 May Street Post Office Box 699 Enfield, New Hampshire 03748 United States of America General enquiries : [email protected] Editorial enquiries : [email protected] Sales enquiries : [email protected] Published by Science Publishers, Enfield, NH, USA An imprint of Edenbridge Ltd., British Channel Islands Printed in India © 2010, copyright reserved ISBN 978-1-57808-668-9 The author and the publisher make no warranty of any kind, expressed or implied, with regard to programs contained in this companion CD. The authors and publisher shall not be liable in any event for incidental or consequential damages in connection with, or arising out of, the furnishing, performance, or use of these programs. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying or otherwise, without the prior permission of the publishers, in writing. The exception to this is when a reasonable part of the text is quoted for purpose of book review, abstracting etc. This book is sold subject to the condition that it shall not, by way of trade or otherwise be lent, re-sold, hired out, or otherwise circulated without the publisher’s prior consent in any form of binding or cover other than that in which it is published and without a similar condition including this condition being imposed on the subsequent purchaser. Chapter 6 Preface This third edition of integrated information on Plant Systematics has largely been influenced by the developments of the first few years of twenty first century. Past two decades have seen development of new tools of biotechnology, vigorous utilization of molecular data in understanding phylogeny, and redefining affinities and arrangements of plant groups. Recent years have also seen disappearance of gaps between numerical and cladistic methodologies, and integration of former into the latter for complete understanding of phylogenetic relationships. These trends have largely influenced the combination of numerical and cladistic methods under one chapter, and enlarged discussion on Molecular Systematics, discussing new concepts, tools and recent achievements. New chapters on Pteridophytes and Gymnosperms have been added for complete understanding of systematics of vascular plants. It is being increasingly realized that actual photographs of plants and plant parts enable better understanding of taxonomic information, the trend usefully exploited by recent publications by Simpson (2006) and Judd et al. (3rd ed., 2008). The present edition incorporates more than 500 colour photographs of plants from diverse families of plants. High-resolution images of these as also the additional plants have been provided in the CD-ROM being supplied along with the book, latter including 772 photographs. This has largely been possible through the kind courtesy of my son Manpreet Singh and daughter- in-law Komal, who sponsored my recent visit to California, and provided me the opportunity to visit and photograph temperate plants in and around California. The book as such contains images of both tropical plants (largely from Delhi), temperate American plants and plants from other parts of the World growing in the Botanical Gardens of University of California and San Francisco Botanical Garden. I wish to record the help rendered by the members of TAXACOM in the identification of some of the American plants. The focus of the present edition has been to further consolidate the information on the principles of plant systematics, include detailed discussion on all major systems of classification, and significantly, also include discussion on the selected families of vascular plants, without sacrificing the discussion on basic principles. The families included for discussion are largely those which have wide representation, as also those that are less iv Plant Systematics known but significant in evaluating the phylogeny of angiosperms. The discussion of the families also has a considerable focus on their phylogenetic relationships, as evidenced by recent cladistic studies, with liberal citation of molecular data. Several additional families have been included for detailed discussion in the present volume. Recent internet revolution has greatly helped in propagating taxonomic information, with numerous searchable databases, online programs for identification and data analysis available for ready reference. The information concerning these has been included at appropriate places in various chapters for easy utilization. In light of this, the separate chapter on web has been omitted. The outputs of computer programs, especially used in molecular studies and construction of phylogenetic trees has been included based on actual or hypothetical data. This will acquaint readers with the handling of raw data and working of computer programs. The author has attempted to strike a balance between classical fundamental information and the recent developments in plant systematics. Special attention has been devoted to the information on botanical nomenclature, identification and phylogeny of angiosperms with numerous relevant examples and detailed explanation of the important nomenclatural problems. An attempt has been made to present a continuity between orthodox and contemporary identification methods by working on a common example. The information on methods of identification using computers has been further enhanced to help better on- line identification. For providing me inspiration for this book, I am indebted to my undergraduate students, who helped me to improve the material through frequent interactions. I am also indebted to my wife Mrs. K.G. Singh for constant support and bearing with my overindulgence with this book. I also wish to acknowledge the help rendered by my son Kanwarpreet Singh at various stages. I wish to record thanks to all the colleagues whose inputs have helped me to improve the information presented here. I also wish to place on record sincere thanks to Dr. Jef Veldkamp for valuable information on nomenclature, Dr. Gertrud Dahlgren for photographs and literature, Dr. P.F. Stevens for literature on APG II and trees from his APweb, Dr. Robert Thorne for making available his 2007 classification, Dr. James Reveal for his help on nomenclatural problems, Dr. D.L. Dilcher for his photograph, Dr. Julie Barcelona and Harry Wiriadinata for photographs of Rafflesia, the authorities of New York Botanical Garden, Missouri Botanical Garden, USA, Royal Botanic Gardens Kew and University of California, Santa Cruz, for photographs used in the book. New Delhi Gurcharan Singh November 2009 Chapter 6 Contents Preface iii 1. PLANTS, TAXONOMY AND SYSTEMATICS 1–14 Plants and Kingdoms of Life 1 Two Kingdom System 1 Two Empires Three Kingdoms 2 Five Kingdom System 2 Six or Seven Kingdoms? 2 The Plant Kingdom 6 Taxonomy and Systematics 7 Basic Components (Principles) of Systematics 8 Aims of Systematics 11 Advancement Levels in Systematics 12 2. BOTANICAL NOMENCLATURE 15–45 Need for Scientific names 15 Why Latin? 16 Development of Botanical Code 16 Contents of Botanical Code 17 Preamble 17 Principles of ICBN 18 Names of Taxa 18 The Type Method 23 Author Citation 25 Publication of Names 26 Rejection of Names 28 Principle of Priority 30 Names of Hybrids 34 Names of Cultivated Plants 35 vi Plant Systematics Unified Biological Nomenclature 35 Draft BioCode 36 PhyloCode 38 3. HIERARCHICAL CLASSIFICATION 46–55 Taxonomic groups, categories and ranks 46 Utilization of categories 48 Species concept 49 Infraspecific ranks 53 Genus 54 Family 54 4. DESCRIPTIVE TERMINOLOGY 56–90 Habit and life span 56 Habitat 57 Roots 57 Stems 58 Leaves 61 Leaf arrangement 62 Leaf duration 63 Leaf incision 63 Stipules 65 Leaf shape 65 Leaf margin 66 Leaf base 66 Leaf apex 67 Leaf surface 68 Venation 69 Inflorescence 69 Racemose types 69 Cymose types 70 Specialized types 71 Flower 71 Calyx 73 Corolla 74 Perianth 74 Androecium 74 Gynoecium 77 Fruit 79 Simple fruits 80 Aggregate fruits 82 Multiple fruits 83 Floral formula 83 Floral diagram 83 5. PROCESS OF IDENTIFICATION 91–127 Specimen preparation 91 Fieldwork 91 Equipment 92 Collection 93 Pressing 93 Contents vii Handling special groups 94 Drying 94 Herbarium methods 95 Botanical gardens 95 Herbaria 101 Pest Control 105 Virtual herbarium 106 Identification methods 108 Taxonomic literature 108 Taxonomic keys 113 Cmputers in identification 120 Interactive keys Id. 121 6.VARIATION, BIOSYSTEMATICS, POPULATION GENETICS AND EVOLUTION 128–148 Types of variation 128 Developmental variation 129 Environmental variation 129 Genetic variation 129 Variance analysis 129 Reproductive systems 131 Outbreeding 131 Inbreeding 135 Apomixis 135 Population genetics 135 Allele frequencies 136 Mating systems 136 Hardy-Weinberg law 136 Evolution 139 Mutation 140 Migration 140 Random genetic drift 140 Natural selection 141 Molecular evolution 143 Neutral theory of evolution 143 Speciation 144 7. TAXONOMIC EVIDENCE 149–209 Morphology 149 Habit 149 Underground parts 150 Leaves 150 Flowers 150 Fruits 150 Anatomy 150 Wood anatomy 150 Trichomes 151 Epidermal features 153 Leaf anatomy 153 Floral anatomy 153 viii Plant Systematics Embryology 154 Families marked out by distinct embryological features 154 Specific examples of the role of embryological data 155 Palynology 156 Pollen aggregation