THE DEVELOPMENTAL ANATOMY OF STEGNOSPERMA (PHYTOLACCACEAE) Item Type text; Dissertation-Reproduction (electronic) Authors Horak, Karl Emanuel Publisher The University of Arizona. Rights Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. Download date 01/10/2021 20:59:10 Link to Item http://hdl.handle.net/10150/281969 INFORMATION TO USERS This was produced from a copy of a document sent to us for microfilming. While the most advanced technological means to photograph and reproduce this document have been used, the quality is heavily dependent upon the quality of the material submitted. The following explanation of techniques is provided to help you understand markings or notations which may appear on this reproduction. 1. The sign or "target" for pages apparently lacking from the document photographed is "Missing Page(s)". If it was possible to obtain the missing page(s) or section, they are spliced into the film along with adjacent pages. This may have necessitated cutting through an image and duplicating adjacent pages to assure you of complete continuity. 2. When an image on the film is obliterated with a round black mark it is an indication that the film inspector noticed either blurred copy because of movement during exposure, or duplicate copy. Unless we meant to delete copyrighted materials that should not have been filmed, you will find a good image of the page in the adjacent frame. 3. When a map, drawing or chart, etc., is part of the material being photo­ graphed the photographer has followed a definite method in "sectioning" the material. It is customary to begin filming at the upper left hand corner of a large sheet and to continue from left to right in equal sections with small overlaps. If necessary, sectioning is continued again—beginning below the first row and continuing on until complete. 4. For any illustrations that cannot be reproduced satisfactorily by xerography, photographic prints can be purchased at additional cost and tipped into your xerographic copy. Requests can be made to our Dissertations Customer Services Department. 5. Some pages in any document may have indistinct print. In all cases we have filmed the best available copy. University Micidrilms International 300 N. ZEEB ROAD, ANN ARBOR, Ml 48106 18 BEDFORD ROW, LONDON WC1R 4EJ, ENGLAND 8117738 HORAK, KARL EMANUEL THE DEVELOPMENTAL ANATOMY OF STEGNOSPERMA (PHYTOLACCACEAE) The University of Arizona PH.D. 1980 University Microfilms International 300 N. Zeeb Road, Ann Arbor, MI 48106 PLEASE NOTE: In all cases this material has been filmed in the best possible way from the available copy. Problems encountered with this document have been identified here with a check mark V . 1. Glossy photographs or pages 2. Colored illustrations, paper or print 3. Photographs with dark background 4. Illustrations are poor copy 5. Pages with black marks, not original copy 6. Print shows through as there is text on both sides of page 7. Indistinct, broken or small print on several pages 8. Print exceeds margin requirements 9. Tightly bound copy with print lost in spine 10. Computer printout pages with indistinct print 11. Page(s) lacking when material received, and not available from school or author. 12. Page(s) seem to be missing in numbering only as text follows. 13. Two pages numbered . Text follows. 14. Curling and wrinkled pages 15. Other University Microfilms International THE DEVELOPMENTAL ANATOMY OF STEGNOSPERMA (PHYTOLACCACEAE) by Karl Emanuel Horak A Dissertation Submitted to the Faculty of the DEPARTMENT OF ECOLOGY AND EVOLUTIONARY BIOLOGY In Partial Fulfillment of the Requirements For the Degree of DOCTOR OF PHILOSOPHY In the Graduate College THE UNIVERSITY OF ARIZONA 19 81 THE UNIVERSITY OF ARIZONA GRADUATE COLLEGE As members of the Final Examination Committee, we certify that we have read the dissertation prepared by Karl E. Horak entitled The Developmental Anatomy of Stegnosperma (Phyt.nl annansap) and recommend that it be accepted as fulfilling the dissertation requirement for the Degree of Doctor of Philosophy . — . _ j- _ Date I <&> DateDate / *4 Date Date Date Final approval and acceptance of this dissertation is contingent upon the candidate's submission of the final copy of the dissertation to the Graduate College. I hereby certify that I have read this dissertation prepared under my direction and recommend that it be accepted as fulfilling the dissertation requirement. 7o HVI Dissertation Director / Date 1 STATEMENT BY AUTHOR This dissertation has been submitted in partial fulfillment of requirements for an advanced degree at The University of Arizona and is deposited in the University Library to be made available to bor­ rowers under rules of the Library. Brief quotations from this dissertation are allowable without special permission, provided that accurate acknowledgment of source is made. Requests for permission for extended quotation from or re­ production of this manuscript in whole or in part may be granted by the head of the major department or the Dean of the Graduate College when in his judgment the proposed use of the material is in the in­ terests of scholarship. In all other instances, however, permission must be obtained from the author. SIGNED: PREFACE The field of systematics deals with similarities and differences of organisms in an effort to recognize patterns, which reveal the evolu­ tionary and developmental origins of the diversity of living things. One is indeed fortunate in a systematic endeavor when a taxon is found exhibiting characteristics that indicate a pivotal phylogenetic posi­ tion in combination with features that are distinctive in closely related taxa yet have arisen convergently in widely separate species. Such a system allows the perceptive scientist to simultaneously examine factors that influence the evolution of the characteristic within a natural group, which shares a fundamental genetic background, and among distantly related species. Anomalous secondary thickening in Stegnosperma os a character­ istic that shows this type of fortuitous pattern. Anomalous secondary growth has long been the object of anatomical investigations but very few studies have dealt with the phenomenon from a position of phyloge­ netic strength. Those authors who did report on the anomaly in a natural group such as the Chenopodiales examined the relatively advanced Amaranthaceae, Chenopodiaceae, and Nyctaginaceae. By turning to the Phytolaccaceae, which possess a wide array of ancestral features, insight can be gained into the evolution of the anomaly from ancestors with normal secondary growth. Many aspects of Stegnosperma make it an ideal organism in which to study the origins of the anomaly from an evolutionary and developmental point of view. iii iv This dissertation, in taking advantage of the merits of the pattern of growth in Stegnosperma, has resulted in a clear picture of the vegetative axis, which is superior to the efforts of many authors in such genera as Avicennia, Bougainvillea, Chenopodium, Phytolacca, and Simondsia. This report described the anomalous condition in Stegnosperma for the first time, illustrates the primary vascular sys­ tem and apical organization, traces the development of the first vascu­ lar cambium in the seedling, shows the relationship between shoot and root architecture and the initiation of the anomaly, follows the longi­ tudinal course of vessels and phloem through the stem, examines trends in cellular dimensions, and demonstrates the path of fluid translocation through the complex vascular interconnections of the secondary plant axis. The author wishes to thank Tony Burgess for assistance in - collecting specimens of j3. halimifolium in the Sierra de las Pintas and a long but futile search in the Pinacates; Dr. J. E. Endrizzi for cyto­ genetic coaching; Dr. R. Felger for the collection of S^. watsonii; Dr. A. C. Gibson for assistance in collecting specimens, especially jS. cubense; Dr. W. B. Heed for critical reading of the manuscript; Linda Horak for patience and encouragement; Dr. C. T. Mason, Jr. for inestimable help and encouragement in the critical final stages; Dr. R. T. Ramage for the use of a camera lucida; Jose Sanchez for pre­ paring many of the line drawings; Dr. 0. G. Ward for the use of the Leitz microscope used in this study and for cytogenetic reagents; and Kent Wood, RBP, for many hours spent showing me the intricacies of photomicrography, copy work, and printing. TABLE OF CONTENTS Page LIST OF ILLUSTRATIONS vii LIST OF TABLES ix ABSTRACT x 1. INTRODUCTION 1 Anomalous Patterns 1 Systematic Distribution of Corpus Lignosum Circumvallatum 7 The Genus Stegnosperma 10 Morphology 10 Cytogenetics 14 Systematics 14 Anomalous Secondary Thickening 17 2. MATERIALS AND METHODS 19 3. DESCRIPTIVE ANATOMY AND ONTOGENY 23 Anatomical Descriptions 27 Wood of Stegnosperma 27 Wood of Stegnosperma cubense 30 Wood of Stegnosperma halimifolium 30 Wood of Stegnosperma watsonii 32 Wood of Small Stems 32 Wood of Large Stems 33 Wood of Roots 33 Wood of Individual Arcs or Rings 34 Extraxylary Tissues 37 Leaf Anatomy 37 Ontogeny of Anomalous Secondary Growth 39 Summary 44 4. THREE-DIMENSIONAL STRUCTURE OF SECONDARY VASCULAR TISSUES . 46 Summary 54 v vi TABLE OF CONTENTS—Continued Page 5. APICAL ORGANIZATION, PRIMARY GROWTH, AND THE INITIATION OF SECONDARY GROWTH 56 Apical Organization 56 Primary Vascular System 57 Trace System Phyllotaxis 57 Procambial Strand Development 60 Residual Meristem 60 Differentiation of Primary Phloem and Xylem 62 Extraxylary Fibers 63 Vascularization of the Seedling 63 Primary root 64 Hypocotyl and Cotyledons 66 Epicotyl 68 Initiation of Secondary Growth 68 Summary 69 6. DISCUSSION 71 Exceptions to Earlier Studies 71 Comparisons Within and Between Genera 72 Diagnosis of the Anomalous Growth 73 Terminology 75 Functional Speculations 78 Stematic Implications 81 APPENDIX A: A TENTATIVE PHYLOGENY OF THE PHYTOLACCACEAE 86 APPENDIX B: STATISTICAL ASSUMPTIONS 92 REFERENCES .