CURRENT CONCEPTS IN PLANT TAXONOMY

Transcription

1 THE SYSTEMATICS ASSOCIATION SPECIAL VOLUME No. 25 CURRENT CONCEPTS IN PLANT TAXONOMY Edited by VM^THEYWOOD and D. M. MOORE v/ Department of Botany, University of Reading, England 1984 Published for the SYSTEMATICS ASSOCIATION by ACADEMIC PRESS (Harcourt Brace Jovanovich, Publishers) LONDON ORLANDO UNIVERSITATS- B1BLIOTHEK SAN DIEGO! SAN FRANCISCO NEW YORK TORONTO MONTREAL SYDNEY TOKYO SAO PAULO

2 Contents List of Contributors Preface v vii Introduction The Current Scene in Plant Taxonomy v. H. HBYWOOD 3 Introduction 3 The rise of numerical taxonomy 4 New sources of taxonomic characters 6 1 Chromosome information cytotaxonomy 7 2 Chemical information - chemosystematics 8 3 Scanning and transmission electron microscopy - microcharacters 9 Biosystematics at the crossroads 10 Floristics 11 Taxonomic indexes and bibliographies 12 Symposia and conference volumes 12 Early evolution of the angiosperms 13 Systems of classification of higher taxa 14 Conclusions 15 References 15 Institutional Resources Libraries and Herbaria j. CULLEN \ 25 Introduction 25 Service to the user 26 Organization and reassessment of priorities 31 Conclusions 37 References 38 Botanic Gardens and Experimental Grounds p. s. ASHTON 39 Introduction 39 The divorce between systematics and living plants 40 The role of gardens in systematics 42 Conclusions 45 References 46

3 Contents Recent Approaches in Morphology and Anatomy Vegetative Morphology - Some Enigmas in Relation to Plant Systematics P. B. TOMLINSON 49 Introduction 49 Theoretical Considerations 51 1 Modular and unitary construction 51 2 Deterministic and opportunistic processes 52 3 Adaptive radiation offloralmechanisms 53 4 Correlation of characters 53 Architecture in systematics 55 1 Lack of systematic association 55 2 Woody monocotyledons 56 3 Shoot morphology 57 4 Seedling morphology 57 Neglected features 57 Structural and functional correlations 58 An evolutionary process 60 1 Evolutionary morphology of Tillandsia usneoides 61 Modular plasticity 63 1 Homology in modular organisms 63 Conclusion 64 Acknowledgements 65 References 65 The Taxonomic Importance of the Leaf Surface c. A. STACE 67 Introduction 68 The use of leaf-surface characters 69 Genetic control and phenotypic plasticity 71 Developmental studies 73 Evolutionary studies 74 Techniques 76 The leaf-surface characters 80 1 Trichomes 80 2 Venation systems 82 3 Epidermal cells 83 4 Stomata 85 5 Cuticular membrane 88 6 Epicuticular secretions 89 7 Special structures 90 Acknowledgements 90 References 90

4 Contents xi 6 Microstructural Features of Seed Surfaces w. BARTHLOTT 95 Introduction 95 Arrangement of seed-coat cells 97 Shape of cells: the primary sculpture 99 Fine relief of the cell wall: the secondary sculpture 101 Epicuticular secretions: the tertiary sculpture 102 Conclusions 102 Acknowledgements 103 References Systematic Anatomy and Embryology - Recent Developments D. F. CUTLER 107 Introduction 108 Secondary xylem 108 Ultrastructure 114 Vascular systems 116 Nodal anatomy 116 Leaf vasculature 116 Epidermal studies Plant surfaces Stomata Trichome types 118 The leaf Morphology and development Photosynthetic pathways Sclereids 119 Floral studies Stigmas Nectaries and secretory tissues Ligules Petals 120 \ Seeds 120 Data banks and computer analysis 121 Embryology Integuments Ovules Taxonomic applications 123 Major anatomical series of publications 124 Acknowledgements 125 References Pollen Features and Plant Systematics s. BLACKMORE 135 Introduction 135 Some recent techniques in palynology 136

5 xii Contents Current approaches in palynology Pollen Floras Ontogenetic studies Pollen form and function Studies of unacetolysed pollen Fundamental structure of the exine 150 Conclusions 151 Acknowledgements 151 References 151 Karyology and Genetics 9 Chromosomal Evidence in Taxonomy j. GREILHUBER 157 Introduction 158 Chromosome techniques 158 Heterochromatin Heterochromatin variation Chromosome banding as a tool in taxonomy 161 Euchromatin 171 Conclusions 175 Acknowledgements 175 References Variation, Polymorphism and Gene-flow within Species Q. o. N. KAY 181 Introduction 182 Dioecy 183 Floral scent 185 Ultraviolet floral characters 186 Floral colour 191 Variation and gene-flow 195 References 196 Ecology and Geography 11 Infraspecific Variation and its Taxonomic Implications R. W. SNAYDON 203 Introduction 204 The nature of variation 205 The patterns of variation The genetic pattern The geographical pattern Analysis of patterns 207

6 Contents xiii Magnitude of variation 208 Interspecific hybrids and gene-flow 209 The role of speciation 211 Infraspecific classification 212 Conclusions 214 References Taxonomy and Geography D. M. MOORE 219 Introduction 219 The changing face of taxonomy Morphology Biosystematics Phytochemistry 226 The changing face of geography 228 Whither now? 230 References 231 Chemistry, Taxonomy and Systematics 13 Chemical Data in Practical Taxonomy j. B. HARBORNE 237 Introduction 237 Newer chemical techniques Analysis of low molecular weight constituents Analysis of proteins and nucleic acids 242 Chemical identification of plant cultivars Crop plants Ornamental plants 247 Chemistry of plant hybrids 250 Chemistry in taxonomic revision 253 References Phytochemistry in Plant Systematics and Evolution K. KUBITZKI 263 Introduction 263 Chemosystematic criteria 264 Chemistry in classification 265 Tracing evolution 268 Causes and mechanisms of phytochemical change 270 Conclusions 272 Acknowledgements 273 References 273

7 xiv Contents Data Processing and Taxonomy 15 Taximetrics To-day j. MCNEILL 281 Introduction 281 The nature of taximetrics Phenetic classification and inumercal taxonomy Objectivity: reality or illusion? The scope of taximetrics 284 Taximetric methods and taxonomic purpose Taximetric applications Grouping of individuals Hierarchical ordering of taxa Continuous variation Other taxonomic situations 294 Conclusions 295 Acknowledgements 296 References Automated Taxonomic Information Systems F. A. BISBY 301 The dream Information content Information meaning Floras, monographs and interconnections Information services 306 The reality Floristic projects Monographic projects 309 Data structure Character structure Character formulation Character selection 317 Data-base structure 317 Concluding remarks 319 Acknowledgements 320 References Cladistic Methodology c. j. HUMPHRIES and v. A. FUNK 323 Introduction 324 Synapomorphies and homology Approaches to systematics Monophyletic groups Parsimony 330

8 Contents. xv Criteria for assessing apomorphies Common is primitive Ontogeny Out-group comparison 336 Homoplasy - parallelism and convergence 341 Reticulate evolution 343 Classification 346 Example 350 Conclusions 355 Acknowledgements 355 References 356 Taxonomic Priorities 18 Completing the Inventory G. T. PRANCE 365 Introduction 366 The problem of rare species in the tropics 368 The problem of neglected areas 377 What is inventory? Special collections Biological data Quantitative inventory Plant groups to be collected Remote sensing 384 The written inventory and data processing 385 The deposition of specimens 386 Conservation and inventory 390 Acknowledgements 392 References Designing Floras for the Future v. H. HEYWOOD 397 Introduction 397 Floras as front-line publications 401 Floras as data-bases 403 Floras and the consumer 404 Floras and the new technology 406 Conclusions 408 References Taxonomic Problems Relating to Endangered Plant Species E. s. AYENSU 411 Subject Index 422 Systematics Association Publications 431