Biosystematics and Phenology of Alnus Maritima (Betulaceae) James Alan Schrader Iowa State University
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Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 2002 Biosystematics and phenology of Alnus maritima (Betulaceae) James Alan Schrader Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Botany Commons, and the Ecology and Evolutionary Biology Commons Recommended Citation Schrader, James Alan, "Biosystematics and phenology of Alnus maritima (Betulaceae) " (2002). Retrospective Theses and Dissertations. 1028. https://lib.dr.iastate.edu/rtd/1028 This Dissertation is brought to you for free and open access by the Iowa State University Capstones, Theses and Dissertations at Iowa State University Digital Repository. It has been accepted for inclusion in Retrospective Theses and Dissertations by an authorized administrator of Iowa State University Digital Repository. For more information, please contact [email protected]. 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ProQuest Information and Learning 300 North Zeeb Road, Ann Arbor, Ml 48106-1346 USA 800-521-0600 NOTE TO USERS This reproduction is the best copy available. UMI' Biosystematics and phenology of Alnus maritima (Betulaceae) by James Alan Schrader A dissertation submitted to the graduate faculty in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Major: Plant Physiology Program of Study Committee: William R. Graves, Major Professor Cynthia Haynes Jeffery lies J. Michael Kelly Richard Schultz Iowa State University Ames, Iowa 2002 UMI Number. 3061863 UMI* UMI Microform 3061863 Copyright 2002 by ProQuest Information and Learning Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, United States Code. ProQuest Information and Learning Company 300 North Zeeb Road P.O. Box 1346 Ann Arbor, Ml 48106-1346 Graduate College Iowa State University This is to certify that the doctoral dissertation of James Alan Schrader has met the dissertation requirements of Iowa State University Signature was redacted for privacy. Major Professor Signature was redacted for privacy. For [ajor Program To Marcy, whose patience and understanding has blessed this work, and whose love has blessed my life. iv TABLE OF CONTENTS ABSTRACT CHAPTER 1. GENERAL INTRODUCTION 1 Introduction 1 Thesis Organization 3 Literature Review 4 Literature Cited 9 CHAPTER 2. ALNUS MARITIMA: A RARE WOODY SPECIES FROM THE NEW 15 WORLD Introduction 15 Classification and Distribution 15 Horticultural Potential 19 Propagation and Production 22 Literature Cited 25 CHAPTER 3. INFRASPECIFIC SYSTEMATICS OF ALNUS MARITIMA 34 (BETULACEAE) FROM THREE WIDELY DISJUNCT PROVENANCES Abstract 34 Introduction 34 Materials and Methods 36 Results 40 Discussion 45 Taxonomic Treatment 53 Literature Cited 63 CHAPTER 4. MOLECULAR SYSTEMATICS OF ALNUS MARITIMA 81 (BETULACEAE) RESOLVED BY ISSR POLYMORPHISMS AND GENESCAN® TECHNOLOGY Abstract 81 Introduction 82 Materials and Methods 83 Results 86 Discussion 87 Literature Cited 90 CHAPTER 5. PHENOLOGY AND DEPTH OF COLD ACCLIMATION IN THE 105 THREE SUBSPECIES OF ALNUS MARITIMA Abstract 105 Introduction 106 Materials and Methods 107 Results 112 Discussion 115 Literature Cited 118 CHAPTER 6. GENERAL CONCLUSIONS 132 General Discussion 132 Recommendations for Future Research 135 Literature Cited 137 V APPENDIX A. BIOSYSTEMATICS: THE NEVER-ENDING STORY 138 APPENDIX B. HERBARIUM SPECIMENS COLLECTED FOR THE 141 INFRASPECIFIC SYSTEMATICS OF ALNUS MARITIMA APPENDIX C. SUPLEMENTARY TABLES AND FIGURES 163 ACKNOWLEDGMENTS 166 vi ABSTRACT Alnus maritima (Marsh.) Muhl. ex Nutt. (seaside alder) is a rare woody plant species found naturally in only three small disjunct populations in the United States. Concern for the conservation of A. maritima and questions regarding the proper classification of its disjunct populations have generated a need for information concerning its ecology and biosystematics, while growing interest in the use of A. maritima in managed landscapes has demonstrated the need for information concerning its ecophysiology and landscape fitness. My first objective was to recount the taxonomic and horticultural history of A. maritima and to report on its current landscape usage and cultivation. Although it has received little attention from horticulturists since its introduction into cultivation over 100 years ago, A. maritima is now being recognized as a stress-resistant large shrub or small tree. My second objective was to derive the infraspecific systematics of A. maritima by morphometric analysis and to classify the three disjunct populations properly. Taxonomic distances were compatible with the modern definition of subspecies, and the subspecific epithets oklahomensis, georgiensis, and maritima were given the three taxa. My third objective was to characterize the molecular systematics of A. maritima according to ISSR polymorphisms. The molecular phytogeny of eight species of Alnus confirmed that A. maritima is most closely related to the other members of subg. Clethropsis and was the first member of its subgenus to diverge. At the infraspecific level, molecular and morphometric phytogenies agreed and showed that subsp. oklahomensis was the first to diverge. My fourth objective was to characterize the cold hardiness of A. maritima in native habitats and in colder climates. Analyses showed that the subspecies are similar in cold hardiness, that plants from all three subspecies can survive mid-winter extremes as low as - 80°C, and that cold acclimation differs between plants grown in colder climates and those in native habitats. Results from these studies support the theory that A. maritima originated in Asia, migrated into North America across the Bering land bridge, and was established over a large range before being forced into its present meager distribution. 1 CHAPTER 1. GENERAL INTRODUCTION INTRODUCTION Alnus maritima (Marsh.) Muhl. ex Nutt. (seaside alder) is a rare woody plant species found naturally in only three small disjunct populations in the United States. Alnus maritima is indigenous to six counties on the Delmarva Peninsula (Eastern Shore of Maryland and southern Delaware), two counties in south-central Oklahoma, and one county in northwestern Georgia. Its presence in Oklahoma and on the Delmarva Peninsula has been recognized for many years, whereas the population in Georgia was not discovered until 1997, when plants were found growing in and around a small swamp that covers approximately 50 hectares (123.5 acres) (Schrader and Graves, 2000). Alnus maritima is a large shrub or small tree that grows to a height of 10 m with several trunks up to 21 cm in diameter. It produces glossy, dark green foliage and is distinguished from other North American alders by its timing of anthesis. Alnus maritima blooms in the autumn, producing red pistillate catkins and pendulous staminate catkins that are bright yellow. All other North American alders bloom in the spring (Furlow, 1979; Stibolt, 1981). The limited distribution of A. maritima has led to its placement on the threatened species lists of the Georgia, Oklahoma, and Maryland Natural Heritage Inventories, where it has been classified as critically imperiled, imperiled, and a watch-list species, respectively (Georgia Natural Heritage Program, 1999; Maryland Heritage and Biodiversity Conservation Program, 1994; Oklahoma Natural Heritage Inventory, 1997). The World Conservation Monitoring Centre lists the status of A. maritima as rare for Delaware and Maryland, vulnerable for Oklahoma, and rare for the World (Walter and Gillett, 1998). Increased concern for the conservation of A. maritima and uncertainty concerning the infraspecific classification of its disjunct populations have generated a need for information on the ecology, population biology, and biosystematics of the three disjunct populations. 2 In the wild, A. maritima exhibits many aesthetic and physiological features that could make it particularly useful as an ornamental plant on sites that are stressful for other woody species. It can be used as a large shrub or small tree, it is tolerant of wet soils, it acquires fixed nitrogen through a symbiotic relationship with Frankia bacteria found in nodules on its roots, its bright yellow catkins are particularly ornamental against its dark green foliage, and early- autumn flowering provides a unique attractiveness at a time of year when few other woody species are in bloom. Increasing interest in the use of A. maritima in managed landscapes has brought a need for information on the ecophysiology and landscape fitness of this species. Assessment of the