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Home , Embryology

Embryology of Angiosperms

Edited by B. M. Johri

With 278 Figures

Springer-Verlag Berlin Heidelberg New York Tokyo 1984 Professor BRIJ MOHAN JOHRI Department of University of Delhi Delhi-ll0007, India

ISBN-13 :978-3-642-69304-5 e-ISBN-13 :978-3-642-69302-1 DOI: 10.1007/978-3-642-69302-1

Library of Congress Cataloging in Publication Data. Main entry under title: Embryology of angiosperms. Ineludes bibliographies. 1. Angiosperms. 2. Botany-Embryology. 1. Johri, B.M. QK495.AlE43 1984 582.13'0433 83-20430. This work is subjeet to copyright. All rights are reserved, whether the whole or part of the material is coneemed, specifically those of translation, reprinting, re-use of illustrations, broadcasting, reproduction by photocopying machine or similar means, and storage in data banks. Under § 54 of the German Copyright Law where copies are made for other than private use a fee is payable to "Verwertungs• gesellschaft Wort", Munich. © by Springer-Verlag Berlin Heidelberg 1984 Softcover reprint of the hardcover 1st edition 1984

The use of registered names, trademarks, etc. in this publication does not imply, even in the absenee of a speeific statement, that such names are exempt from the relevant proteetive laws and regulations and therefore free for general use.

2131/3130-543210 Dedicated to Professor John M. Coulter and Professor Charles J. Chamberlain Foreword

Thirty-four years have elapsed since the publication of the late Professor P. Maheshwari's text, An Introduction to the Embryology ofAngiosperms, a work which for many years served as an invaluable guide for students and a rich source book for research workerso Various texts dealing with sections of the braad spectrum oftopics encompassed by Maheshwari in his book have appeared in the interim, but a compendious modem work dealing with the whole field has been lacking. This present volume splendidly meets the need, and it is altogether fitting that Professor B. M. lohri, long an associate and close colleague of Professor Maheshwari and himself a prolific contributor to the subject, should have undertaken the task of editing it. When Maheshwari wrote, it was stiIl feasible for one author to handIe the subject, but today even someone with his fine bread th of vision and depth of understanding could not, alone, do it justice. So the effort has to be a collaborative one; and Professor lohri's achievement has been to bring together a team of authoritative collaborators, assign them their responsibilities, and put them to work to produce a text as integrated in its treatment as the diversity of the subject would allow. The product vividly illustrates the advances that have been made in the study of angiosperm reproductive systems in the last 30 years, and the book is surely destined to become the new standard for student and researcher alike. Like many surveys of its kind, the text inevitably shows just how dependent pragress during the last few decades has been on the advent of new technologies. The great observers of earlier generations reached the limits set by the resolution of the optical microscope in their investigations of the cytological and karyological phenomena associated with plant re• production, and were restricted further by the preparation techniques they had available. Their modem successors have been blessed with new extensions of vision - on the one hand through the advent of electron micrascopy, and on the other, through the further technical development of optical micrascopy, marked, for example, by the introduction of phase and differential interference contrast, fluorescence techniques and image-processing systems. At the same time, specimen handling methods have improved apace, and the crumbling ofhitherto stoutly maintained interdisciplinary barriers has meant that many workers today have gained a new competenee to interpret what they observe through the support of physiological and biochemical experimentation. All this adequately accounts for the flood of new information. Yet, if one VIII Foreword message emerges from the present text as a whole - urged by author after author - it is that we are now but on the threshold of a new wave of discovery. No living group shows the diversity of reproductive method to be seen in the angiosperms; and no task in the whole field of biological research is more important for mankind than working the systems out and finding how to manipulate them for practical ends, for after all the flowering plants provide the indispensable basis of human life on earth. This volume is not only an epitome ofknowledge, but an invitation and a challenge - a challenge, particularly, for the next generation of workers, some of whom may weIl find in its pages good reason for ignoring the facile appeal oftest-tube in favour of making their contribution towards finding out more about how real plants go about the job of reproducing.

July 1984 J. HESLOP-HARRISON, F.R.S. Royal Society Research Professor University CoIlege of Wales Welsh Plant Breeding Station Plas Gogerddan (near Aberystwyth) Great Britain Preface

Since the publication of Recent Advances in the Embryology of Angio• (ed. P. Maheshwari) in 1963, there has been phenomenal progress in almost all areas of reproduction in flowering plants. This progress has resulted from investigations based on optical, electron (TEM, SEM), fluorescence, phase contrast, and interference (Nomarski effect) micro• scopy, cytochemistry, histochemistry, and . However, all this knowledge is scattered in a large number of periodicals and it has become a formidable task for both teachers and students to collect the necessary information. Hence this volume Embryology of Angiosperms - an advanced treatise comprising 16 chapters written by specialists who have devoted years of study to the subject. The significant advances of the last 20-30 years have been discussed. The authors have raised several questions to seek new information, and have made appropriate mention of many unsolved probIems. The text is adequately illustrated with line drawings and half-tones, including electron micrographs. Every effort has been made to present a comprehensive up-to-date account. I have earnestly endeavoured to achieve uniformity in the format. Suggestions for further improvement would be most welcome. I have no doubt that post-graduate and research students will find Embryology of Angiosperms a good source material. To those teaching "reproduction in flowering plants", the volume offers a fount of ready• made material.

July 1984 B.M. JOHRI Acknowledgements

Through Dr. G. A. Nogler, Dr. Konrad F. Springer invited me to prepare an English translation of Professor A. Rutishauser's book Embryologie und Fortpjlanzungsbiologie der Angiospermen. My ex• perience of teaching undergraduate and postgraduate students for over three decades at the Universities of Agra, Rajasthan and Delhi has provided a deep insight into the various aspects of plant embryology. Also, over a span of almost 50 years, I have had unique opportunities to discuss problems of angiosperm embryology with eminent embryologists during my numerous visits both in India and abroad, and at inter• national meetings. The idea of editing avolume consisting of contribu• tions on recent developments in the embryology of angiosperms emerged out of these interactions. Dr. Springer readily agreed to my suggestion, and I am deeply indebted to him. Professor J. Heslop-Harrison has done me a great favour in agreeing to prepare the "Foreword" to this volume. I am grateful to the authors who accepted my invitation to write the chapters. The manuscripts were read by my colleagues in the University of Delhi and I especially thank Professor N.S. Rangaswamy, Dr. N.N. Bhandari, Dr. M.R. Vijayaraghavan, Dr. K.R. Shivanna and Dr. S. Natesh for offering valuable suggestions. I greatly appreciate the help rendered by Dr. K. B. Ambegaokar, who redrew several diagrams, reassembled many plates of illustrations, and prepared the indiees. Professor Dr. G. Melchers (Tübingen) provided photographs of the tomato+potato somatic hybrid. Professor Dr. E. Battaglia (Rome) sent a reprint containing the original diagrams of Fritillaria type of sac. Professor Dr. F. Pospisil (Prague) sent photographs of poIlen embryo sacs. Professor Dr. O. Erdelska (Bratislava) prepared an illustrated write-up on the role ofmicrocinematography in embryology. Dr. Scott D. Russell (Norman) sent me his unpublished manuscripts, and electron micrographs of male and fertilization in Plumbago. Dr. R. Wunderlieh (Vienna), Dr. M. Luxova (Bratislava), Dr. L. Ahl• strand (Göteborg) and Dr. B.A. Fineran (Christchurch) made availab1e the literature needed. I am much obliged to all ofthem for their gracious help. The facilities at the Department of Botany, University of Delhi, made it possible to prepare the Embryology of Angiosperms, and I am grateful to Professor S.C. Maheshwari, Professor H.Y. Mohan Ram, Professor R.N. Kapil and Professor R.N. Chopra (present of the Depart• ment) who have been continuously 100king after my interest since I XII Acknowledgements retired in 1974. I have received much inducement to complete the book expeditiously from my wife Raj, my daughter-in-Iaw Meera, and my son Lalit. My sincere appreciation is extended to Mr. R. K. Gupta for typ• ing several chapters, and to Mr. Krishan Lal for preparing some illustrations. From the house of Springer, I am especially thankful to Dr. Dieter Czeschlik, Life-Science Editor, for valuable advice, to the Copy-Editor who made much improvement in the text, to Mrs. Linda Teppert for processing the publication, and to Miss Claudia Grössl who looked after the production of this book.

July 1984 B.M. JOHRI Contents

1 Embryology: Then and Now B.M. JOHRI and K.B. AMBEGAOKAR (With 22 Figures)

1.1 Introduction ...... 1 1.2 Techniques to Study Embryology 2 1.3 Embryo Sacs in Anthers 5 1.3.1 Leptomeria 5 1.3.2 Calotis...... 6 1.3.3 Hyacinthus ...... 6 1.4 Fritillaria Type of Embryo Sae 12 1.5 Unusual Embryological Features in Loranthaceae 14 1.5.1 Ovary-Ovule Complex 14 1.5.2 Embryo Sac. 16 1.5.3 Endosperm .... . 18 1.5.4 Embryo ...... 19 1.5.5 Reproductive Calendar in Struthanthus vulgaris 21 1.6 of the Ovule and Seed . 22 1.6.1 Vascular Supply . 23 1.6.2 Haustoria ...... ". 23 1.6.3 Transfer Cells...... 28 1.7 Role of Persistent Pollen Tubes 30 1.8 of Doubtful Origin 32 1.8.1 Antipodal Embryos . . . . . 33 1.8.2 Endospermal Embryos . . . . 33 1.9 Gymnospermous Characters in Angiosperms 37 1.9.1 Tambourissa 37 1.9.2 Butomopsis . . . 39 1.9.3 Paeonia .... 42 1.10 Future Research. 43 References . . . 47

2 The Microsporangium N.N. BHANDARI (With 21 Figures) 53

2.1 Introduction ...... 53 2.2 Morphology and Structure 53 2.3 .. 55 2.4 Wall Layers...... 57 XIV Contents

2.4.1 Epidermis .. 57 2.4.2 Endothecium . 58 2.4.3 Middle Layers. 60 2.4.4 Tapetum ... 60 2.5 Ubisch BodiesjOrbicules 77 2.5.1 Origin ...... 79 2.5.2 Relation to Exine Deposition: By-Product 82 2.6 Tapetal Membrane: Structure, Origin, and Significance 83 2.7 Pollenkitt and Tryphine ...... 85 2.8 Sporogenous Tissue: Ultrastructure ...... 88 2.8.1 Cytoplasmic Membranes and Ribosome Population 88 2.8.2 Nuc1eus ...... 90 2.8.3 Nuc1eolar Cyc1e ...... 92 2.8.4 Cytoplasmic Organe1les During Meiosis. . . 94 2.8.5 Plasmodesmata and Cytoplasmic Conneetions 95 2.9 Initiation and Control of Meiosis . . . . . 97 2.9.1 Duration of Meiosis ...... 99 2.9.2 Synthesis of Callose: Deposition and Significance 100 2.9.3 Cytokinesis ...... 106 2.9.4 Cellulosie Wall of Mierospore Mother 107 2.10 Some Unusual Features 109 2.11 Conc1usions . 110 References 111

3 The Ovule F. BOUMAN (With 21 Figures) 123 3.1 Historieal. . . . . 123 3.2 Ovular Morphology 125 3.3 Ovule Initiation . 126 3.4 Nucellus .... 128 3.5 Megasporogenesis 131 3.6 Integuments. . . 138 3.7 Types of Ovules . 144 3.8 Vascular Supply of the Ovule 147 3.9 Special Structures . . 148 3.10 Ovule Reduction 151 3.11 Conc1uding Remarks . 153 References . . . . 153

4 The Female Gametophyte M.T.M. WILLEMSE and J.L. VAN WENT (With 16 Figures) . 159 4.1 Introduction ...... 159 4.2 Types of Megagametophyte Development . 159 4.3 Development of the Megagametophyte 164 4.3.1 The Megaspore . . . . : ...... 164 Contents xv

4.3.2 The Coenoeytic Megagametophyte. . 165 4.4 The Relation with the Nueellar Tissue 168 4.5 Organization of the Embryo Sae . 170 4.5.1 The Synergids. . 174 4.5.2 The Cell . . . 183 4.5.3 The Central Cell .. 185 4.5.4 The Antipodal Cells 188 4.6 Female Gametophyte Development 190 Referenees ...... 191

5 The Polleo Graio R.B. KNOX (With 24 Figures)...... 197 5.l Introduction...... 197 5.2 Pollen Strueture and Cytoehemistry 198 5.2.l Pollen Shape . . . . 199 5.2.2 Pollen Cytology . . . 199 5.2.3 Pollen-wall Strueture . . 204 5.2.4 The Pollen Tube. . . . 208 5.2.5 Struetural of Pollen for Dispersal . . 210 5.3 Formation of Pollen . . . . 225 5.3.l Cytology of Development . . 225 5.3.2 The Primexine...... 232 5.3.3 Establishment of Apertures . 237 5.3.4 Exine Differentiation and Maturation . 238 5.3.5 Intine Synthesis and Deposition . . . . 242 5.3.6 Meehanism of Cohesion in Composite Pollen . 244 5.3.7 Pollen Sterility ...... 245 5.4 Pollen Germination and Pistil Interaetions . . 245 5.4.l Pollen Quality ...... 245 5.4.2 Pollen Germination and Tube Development . . 247 5.4.3 Diagnostie Landmarks of Pollination. . . . . 249 5.4.4 Role of Pollen in Fertilization and Seed-setting . 252 5.5 Pollen-wall Proteins and Allergens . . . 253 5.6 Conelusions and Future Developments . 259 Referenees ...... 261

6 Fertilizatioo J.L. VAN WENT and M.T.M. WILLEMSE (With 13 Figures) . . 273 6.l Introduction ...... · 273 6.2 Stigma and St yle ...... · 273 6.2.1 Funetion and Strueture of the Stigma · 273 6.2.2 The of the Stigma Covering 275 6.2.3 Funetion and Strueture of the St yle · 277 6.3 Pollen Germination . . · 279 6.3.1 Stieking and Hydration...... · 279 XVI Contents

6.3.2 Pollen Tube Formation and Growth 281 6.3.3 The Cell 283 6.4 Pollen-Pistil Interaction. 284 6.4.1 Pollen Recognition, Acceptance, and Rejection 284 6.4.2 Pollen Incompatibility 286 6.4.3 Entry of Pollen Tube into Stigma and Style . 289 6.4.4 Pollination Effects . 291 6.5 Entrance and Discharge in Embryo Sae. 292 6.5.1 Course of the Pollen Tube 292 6.5.2 Entry into the Embryo Sae 294 6.5.3 Growth Through the Filiform Apparatus 297 6.5.4 Entry into the Synergid . 298 6.5.5 Transfer of Tube Content . 301 6.6 Fusion of Gametes . 302 6.6.1 Fusion of Nuclei 305 6.7 The Progamic Phase and Fertilization 308 References 309

7 The Endosperm M.R. VIJAYARAGHAVAN and K. PRABHAKAR (With 30 Figures) 319 7.1 Introduction 319 7.2 Nuclear Endosperm 319 7.2.1 Wall Formation. 322 7.2.2 Cucurbitaceae . 322 7.2.3 Leguminosae 323 7.2.4 Palmae. 323 7.2.5 Proteaceae 324 7.2.6 Histochemistry and Ultrastructure 324 7.3 Cellular Endosperm 330 7.3.1 Acanthaceae 330 7.3.2 Cyrillaceae 330 7.3.3 Gesneriaceae 330 7.3.4 Icacinaceae . 331 7.3.5 Santalaceae . 331 7.3.6 Loasaceae 332 7.3.7 Loranthaceae 332 7.3.8 Scrophulariaceae 335 7.3.9 Histochemistry and Ultrastructure 337 7.4 Helobial Endosperm . 338 7.4.1 Salient Features in Monocotyledons 339 7.4.2 Histochemistry and Ultrastructure 341 7.5 Ruminate Endosperm 342 7.6 Central Cell . 345 7.6.1 Central Cell Cytoplasm . 346 7.6.2 Central Cell Nucleus . 349 7.6.3 Covering of the Central Cell 349 Contents XVII

7.7 Wall Formation in Endosperm ...... 350 7.8 Cytology of the Endosperm...... 355 7.9 Reserve Materials in Developing Endosperm 361 7.9.1 Protein Bodies ...... 361 7.9.2 Starch...... 363 7.10 Embryo-Endosperm Relationship . . . . . 364 7.11 Incorporation of Nucellus and Integument in Endosperm Formation ...... 368 7.12 Conelusions and Prospects 369 References ...... 370

8 The Embryo S. NATESH and M.A. RAU (With 29 Figures) 377

8.1 Historieal...... 377 8.2 ...... 378 8.2.1 Structure and Composition 379 8.2.2 Size Adjustments . . 382 8.2.3 Polarity ...... 383 8.3 Early Embryogenesis . 384 8.3.1 Cell Pattems . . . . 384 8.3.2 Tetrad, Quadrant, and Octant Proembryos 385 8.3.3 Stages Leading to Mature Embryo. . . . 387 8.4 Classification Based on Early Development of the Embryo 388 8.4.1 Systems Suggested by Schnarf and Johansen. 388 8.4.2 System Suggested by Soueges . 392 8.4.3 Other Systems of Classification 393 8.5 Differentiation in Embryo 397 8.6 Dicot and Monocot Embryo 398 8.7 The Grass Embryo. . . . . 400 8.8 The Embryo in Palms . . . 403 8.9 Ultrastructural and Cytochemical Aspects . 405 8.10 Suspensor: Structure and Function . 414 8.11 Deviations from U sual Development 424 8.11.1 Embryogeny in Paeonia 424 8.1l.2 Embryos Devoid of Organs 425 8.1l.3 Chimeral Embryos. . 430 8.12 Coneluding Remarks . 433 References . . . . . 434

9 Polyembryony K.K. LAKSHMANAN and K.B. AMBEGAOKAR (With 12 Figures) . 445

9.1 Introduction 445 9.2 Classification . 446 XVIII Contents

9.2.1 Simple Polyembryony 447 9.2.2 Multiple Polyembryony . 447 9.3 Nucellar Polyembryony . 447 9.3.l Rutaceae . 448 9.3.2 Anacardiaceae . 452 9.3.3 Myrtaceae 452 9.3.4 Cactaceae. 454 9.3.5 Orchidaceae. 454 9.4 Integumentary Polyembryony 454 9.4.l Endothelial Polyembryony 455 9.5 Zygotic and Suspensor Polyembryony 456 9.5.l Zygotic Polyembryony . 456 9.5.2 Suspensor Polyembryony 458 9.6 Synergid Polyembryony 458 9.6.1 Twins and Triplets . 461 9.7 Polyembryony in Hybrids . 463 9.8 Causes of Polyembryony 465 9.9 Induction of Polyembryony 466 9.10 Utilization of PluraI Embryos 470 References 470

10 Gametophytic Apomixis G.A. NOGLER (With 8 Figures) . 475 1O.l Introduction 475 10.1.1 Definitions 475 10.1.2 Synonyms 476 10.1.3 Remarks on Terminology . 477 10.2 Embryology of Gametophytic Apomicts 477 1O.2.l Development of Unreduced Embryo Sacs . 477 10.2.2 Formation of Endosperm and Embryo . 487 10.2.3 Male Meiosis and the Male Gametophyte . 493 10.3 Apomixis and Sexuality 494 10.3.1 Sexual Potentials in Gametophytic Apomiets 494 10.3.2 Possibilities of Influencing the Degree of Apomixis . 495 10.4 Causes and Consequences of Apomixis . 497 10.4.1 Heterozygosity and Variability . 497 10.4.2 Causes of Gametophytic Apomixis; Components of Apomixis in Sexual Plants 498 10.4.3 Apomixis and Polyploidy . 500 10.4.4 Agamic Species Cornplexes and Their Evolution 501 10.5 Geneties of Gametophytie Apomixis 503 10.5.1 Dominant or Recessive Inheritance? 503 10.5.2 Some Critical Remarks . 504 10.5.3 Some Results, Conelusions, and Prospects . 506 10.6 Apomixis and Breeding. Conelusions . 508 References 510 Contents XIX

11 Role of Polyploidy in Reproductive Organs and Tissues F. D'AMATO (With 16 Figures) ...... 519

11.1 Introduction ...... 519 11.2 Methods of Polyploidization and Ploidy Determination . 519 11.2.1 Acytokinetic Mitosis (AM) · 520 11.2.2 SpindIe Fusion (SF) . . . · 520 11.2.3 Restitutional Mitosis (RM) · 520 11.2.4 Endomitosis (Em) . . . . · 520 11.2.5 Chromosome Endoreduplication (Er) . · 521 11.2.6 Ploidy Determination . . . · 522 11.3 Anther ...... · 523 11.3.1 Anther Wall and Connective · 523 11.3.2 Tapetum ... · 523 11.3.3 Pollen Grains . · 529 11.4 Ovule ... . · 530 11.4.1 Nucellus .. . · 530 11.4.2 Integument(s) and Endothelium · 530 11.5 Embryo Sae. 531 11.5.1 Egg Cell ...... 531 11.5.2 Synergids ...... 532 11.5.3 Proendospermic Cell . 533 11.5.4 Antipodal Cells . . . 534 11.6 Endosperm ..... 537 11.6.1 Origin and Types of Endosperm . 537 11.6.2 Polyploidy in the Endosperm 537 11.7 Embryo ...... 543 11.7.1 Embryo Proper ...... 543 11.7.2 Suspensor ...... 546 11.7.3 Nonzygotic Embryos .... 557 11.8 Physiological Role of Polyploidy . 558 11.9 Future Research . 560 References ...... 561

12 The Seed: Structure F.D. BOESEWINKEL and F. BOUMAN (With 16 Figures) . 567

12.1 Introduction . . . 567 12.1.1 Importance of Seeds · 567 12.1.2 Historieal Survey . · 568 12.2 Structure of Seeds . · 569 12.2.1 General Morphology . · 569 12.2.2 Vascular Supply of the Seed . · 571 12.2.3 Seed Types ...... · 572 12.2.4 Development and Structure of Seed-coats . · 575 12.2.5 Differentiation ...... · 579 xx Contents

12.2.6 The Seed-eoat Surfaee ...... 585 12.2.7 Stomata in Seed-eoats ...... 589 12.3 Special Struetures, Adaptations, and Funetions 590 12.3.1 Sareotestal Seeds 590 12.3.2 Arillate Seeds . 590 12.3.3 Jaeulator. . . 594 12.3.4 Winged Seeds . 594 12.3.5 Haired Seeds . 594 12.3.6 Dust and Balloon Seeds 595 12.3.7 Hydroehorie Seeds. . . 596 12.3.8 Mucilage Seeds . . . . 596 12.3.9 Aetive Dispersal of Seeds (Autoehorie Seeds) 598 12.3.10 Color of Seeds ...... 598 12.4 Adaptations to Germination 599 12.4.1 Opereula...... 599 12.4.2 Imbibition Lids ...... 602 12.4.3 Epistase and Hypostase. . . 602 12.5 Rumination and Labyrinth Seeds 603 12.5.1 Labyrinth Seeds. . . 605 12.6 Storage Tissue. . . . 605 12.7 Conc1uding Remarks . 607 Referenees . . . . . 608

13 The Seed: Germioatioo J.V. JACOBSEN (With 7 Figures) 611

13.1 Introduction..... 611 13.2 General Considerations . 612 13.2.1 InternaI Morphology. . 612 13.2.2 Composition of Seeds and Reserve Foods . 613 13.3 Germination: Struetural, Compositional, and Physiological Changes . . . . 614 13.3.1 Dicotyledons ...... 616 13.3.2 Monoeotyledons...... 629 13.4 Storage and Aging of Seeds: Strueture and Physiology 637 References ...... 639

14 Embryology aod Taxooomy J.M. HERR, JR. (With 11 Figures) . 647 14.1 Introduction..... 647 14.2 Embryological Features of Taxonomic Importance . 649 14.3 Applications of Embryology to Problems of Family Relationships . 651 14.3.1 Podostemaceae ...... 651 Contents XXI

14.3.2 Basellaeeae 655 14.3.3 Staehyuraeeae . 657 14.3.4 Frankeniaeeae. 659 14.3.5 Tropaeolaeeae. 661 14.3.6 Salvadoraeeae . 662 14.3.7 Centrolepidaeeae 664 14.4 Applieations of Embryology to Problem s of Taxonomic Stmeture Within Families . 666 14.4.1 Aizoaeeae 667 14.4.2 Vaeeiniaeeae 667 14.4.3 Zannichellia . 669 14.5 Applieations of Embryology to Problem s of Generie Affinity and Assignment 671 14.5.1 Ploiarium. 671 14.5.2 Filieium 672 14.5.3 Nyctanthes-Jasminum. 673 14.5.4 Ophiopogon . 677 14.5.5 Kyllinga 678 14.5.6 Burmannia pusilla 679 14.6 Contributions of Embryology to Taxonomic Problem s StilI Unsolved . 680 14.6.1 Erythroxylaeeae-Linaeeae . 680 14.6.2 Theligonaeeae . 681 14.6.3 Blandfordia . 682 14.6.4 Philydraeeae 682 14.6.5 Erioeaulaeeae . 683 14.7 Confirmation or Alteration of Earlier Conelusions 683 14.7.1 Caetaeeae. 684 14.7.2 Garryaeeae . 684 14.7.3 Oro banehaceae 684 14.7.4 Pentaphragma . 685 14.8 Embryology in Relation to - the Prospect . 685 14.8.1 Cornus . 686 14.8.2 Glyeine and Phaseolus 688 14.8.3 Eustachys petraea and E. glauca 690 References 691

15 Homologies and Phylogeny M. FAVRE-DuCHARTRE (With 17 Figures). 697

15.1 Introduction ...... 697 15.1.1 Sexuality and Overall Phylogeny . 699 15.2 Mierosporangia . . . . . 700 15.2.1 Microsporangium Wall. . . . . 700 15.2.2 Microsporangium Content . . . 701 15.2.3 Microsporangium Number and Position 702 XXII Contents

15.3 Megasporangia... 703 15.3.1 General Strueture . . 703 15.4 Ontogeny of NuceHus 705 15.4.1 Tapetum/Endothelium 706 15.4.2 Megasporangium Content 706 15.4.3 A Proposed Maeroevolution of Meiosporie Struetures 706 15.5 Male Gametophyte . . . 707 15.5.1 Extrinsie to Angiosperms . 707 15.5.2 Intrinsie to Angiosperms . 709 15.6 Fema1e Gametophyte 711 15.6.1 Female Sexual Struetures in Chlorophyta Extrinsie to Angiosperms . . . . . 711 15.6.2 Embryo Sae...... 713 15.6.3 Diversity in Embryo Saes...... 715 15.6.4 Ontogeny of Embryo Sae as Compared to Female Gametophyte of Taxus...... 717 15.7 PoHen Reeeption by Female ... . . 717 15.7.1 Fertilization...... 719 15.7.2 Double Fertilization, Extrinsie to Angiosperms 719 15.7.3 Intrinsie to Angiosperms . . . 721 15.7.4 Cyto10gy of Zygote Formation ...... 721 15.8 Embryogenesis...... 723 15.8.1 A1buntinogenesis (or Endosperm Formation) in Angiosperms 724 15.8.2 Embryo ...... 726 15.9 Seed...... 728 15.9.1 Time Re1ations in the Deve10pment of Seed . 728 15.9.2 Diversity in Seed Structure ...... 730 15.10 Conc1uding Remarks...... 730 15.10.1 Questions Raised by Natural Diversities . . 730 15.10.2 Questions Raised by Suggested Experiments .731 Referenees ...... 731

16 Experimental Embryology B.M. JOHRI and P.S. RAo (With 15 Figures) 735 16.1 Introduction ...... 735 16.2 The ProbIems: Role of Experimental Embryology 736 16.3 Teehniques of CeH, Tissue, and Organ Culture. 738 16.4 Floral Organs and Buds 739 16.4.1 In Vivo Studies . . . . . 739 16.4.2 In Vitro Studies . . . . . 740 16.5 Anther and PoHen Culture 743 16.5.1 CulturaI Proeedure and Nutritional Requirements 743 16.5.2 Anther Culture 746 16.5.3 PoHen Culture...... 749 Contents XXIII

16.5.4 The Pollen Plants ...... 751 16.5.5 Use of Haploids...... 751 16.6 Ovary, Ovule, and Nucellus Culture 752 16.6.1 Ovary Culture. . 753 16.6.2 Ovule Culture. . . . . 754 16.6.3 Nucellus Culture. . . . 757 16.7 Control of Fertilization . 761 l6.7.l Intra-ovarian Pollination and Fertilization 761 16.7.2 In Vitro Pollination of Ovules and Fertilization 762 16.7.3 Inter- and Intrageneric Hybrids 764 16.8 Endosperm Culture . 765 16.8.1 Immature Endosperm . . . . 766 16.8.2 Mature Endosperm . . . . . 766 16.8.3 Embryo-Endosperm Relationship 766 16.8.4 Organogenesis in Endosperm Cultures 767 16.9 Embryo Culture. . . . . 769 16.10 Polyembryony...... 773 16.11 Control of Embryogenesis . 777 l6.ll.l Loss of Embryogenic Potency 778 16.11.2 Ontogeny of Embryos . . . 779 16.l2 Protoplast Culture. . . . . 782 16.12.1 Embryogenesis and 782 16.l2.2 Protoplast Fusion and Somatic Hybridization 784 16.12.3 "Pornatoes" and "Topatoes" 788 16.l3 Concluding Remarks . 788 References ...... 789

Plant Index . 803

Subject Index. 819 Contributors

AMBEGAOKAR, K.B., Department of Botany, University of Delhi, Delhi 110007, India BHANDARI, N.N., Department of Botany, University of Delhi, Delhi 110007, India BOESEWINKEL, F.D., Hugo de Vries Laboratory, University of Amster• dam, 1018 DD Amsterdam, The Netherlands BOUMAN, F., Hugo de Vries Laboratory, University of Amsterdam, 1018 DD Amsterdam, The Netherlands

D'AMATo, F., Institute of , University of Pisa, 56100 Pisa,

FAVRE-DuCHARTRE, M., Botanical Laboratory, Faculty of Science, University of Reims, 51062 Reims Cedex, France

HERR, J.M., JR., Department of Biology, University of South Carolina, Columbia, SC 29208, USA

JACOBSEN, JOHN V., Division ofPlant Industry, Commonwealth Scientific and Research Organization, Canberra City, A.C.T. 2601, Australia

JOHRI, B.M., Department of Botany, University of Delhi, Delhi 110007, India KNOX, R.B., Plant CelI Biology Research Centre, School of Botany, University of Melbourne, Parkville, Victoria 3052, AustraHa LAKSHMANAN, K.K., Department of Botany, Bharathiar University, Coimbatore 641041, India NATEsH, S., Department of Botany, SGTB Khalsa ColIege, University of Delhi, Delhi 110007, India. (Present address: Department of Science and Technology, Technology Bhavan, New Mehrauli Road, New Delhi 110016, India NOGLER, G.A., Institute for General Botany, Federal University of Technology (ETH), 8092 Zurich, Switzerland PRABHAKAR, KUMKUM, Department of Botany, Maitreyi ColIege, University of Delhi, Netaji Nagar, New Delhi 110023, India XXVI Contributors

RAo, P.S., Plant Morphogenesis and Section, Bio• Organic Division, Bhabha Atomic Research Centre, Trombay, Bombay 400085, India RAU, M.A., Department of Applied Botany, University of Mysore, Manasa Gangotri, Mysore 570006, India (962 Lakshmipuram, Mysore 570004, India) VAN WENT, J.L. Department of Plant Cytology and Morphology, Agricultural University, Botanical Laboratory, 6703 BD Wageningen, The Netherlands VIJAYARAGHAVAN, M.R., Department of Botany, University of Delhi, Delhi 110007, India WILLEMSE, M.T.M., Department of Plant Cytology and Morphology, AgriculturaI University, Botanical Laboratory, 6703 BD Wageningen, The Netherlands