Iowa State University Capstones, Theses and Retrospective Theses and Dissertations Dissertations 1986 Systematics of Chusquea section Chusquea, section Swallenochloa, section Verticillatae, and section Serpentes (Poaceae: Bambusoideae) Lynn G. Clark Iowa State University Follow this and additional works at: https://lib.dr.iastate.edu/rtd Part of the Botany Commons Recommended Citation Clark, Lynn G., "Systematics of Chusquea section Chusquea, section Swallenochloa, section Verticillatae, and section Serpentes (Poaceae: Bambusoideae) " (1986). Retrospective Theses and Dissertations. 7988. https://lib.dr.iastate.edu/rtd/7988 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. 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SYSTEMATICS OF CHUSQUEA SECTION CHUSQUEA, SECTION SWALLENOCHLOA, SECTION VERTICILLATAE, AND SECTION SERPENTES (POACEAE: BAMBUSOIDEAE) lowa State University PH.D. 1986 University l\^icrofilms INTGRNÂTIONÂI 3»N.Zeebmoad, Ann ArbonMl48106 Copyright 1986 by Clarl<, Lynn G. Ail Rights Reserved 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 t^xt 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. Dissertation contains pages with print at a slant, filmed as received 16. Other . University Microfilms International Systematica of Chusquea section Chusguea, section Swallenochloa, section Verticillatae, and section Serpentes (Foaceae: Bambusoideae) by Lynn 6. Clark A Dissertation Submitted to the Graduate Faculty in Partial Fulfillment of the Requirements for the Degree of DOCTOR OF PHILOSOPHY Department: Botany Major: Botany (Taxonomy) Approved; Signature was redacted for privacy. n Charge of Major Work Signature was redacted for privacy. For the Major Department Signature was redacted for privacy. Iowa State University Ames, Iowa 1986 Copyright Lynn G. Clark, 1986. All rights reserved. il TABLE OF CONTENTS Page I. INTRODUCTION I II. MATERIALS AND METHODS 4 A. Herbarium Studies 4 B. Field Studies 5 C. Chromosome Studies 5 D. Morphological Studies 6 E. Light Microscopy 7 F. Scanning Electron Microscopy 8 III. CYTOLOGY AND REPRODUCTIVE BIOLOGY 9 A. Cytology 9 B. Reproductive Biology 12 1. Phenology 12 2. Hybridization 20 IV. VEGETATIVE MORPHOLOGY 28 V. ECOLOGY 49 VI. LEAF ANATOMY 60 A. Light Microscopy 60 1. Discussion 60 2. Descriptions 64 B. Scanning Electron Microscopy 75 1. Discussion 75 2. Descriptions 80 VII. SYSTEMATICS 113 A. Taxonomlc History 113 ill Page B. Taxonomlc Treatment 118 C. Cladlstlc Analysis 124 D. Evolution and Blogeography 141 VIII. TAXONOMIC DESCRIPTIONS 155 A. Chusquea Kunth 155 B. Chusquea section Chusquea 158 C. Chusquea sectlo Swallenochloa 177 D. Chusquea sectlo Vertlclllatae 267 E. Chusquea sectlo Serpentes 306 IX. LITERATURE CITED 334 X. ACKNOWLEDGMENTS 347 XI. APPENDIX A: SPECIES INCLUDED IN CHUSQUEA 350 XII. APPENDIX B: INVALID AND EXCLUDED TAXA 370 A. Species Excluded from Chusquea 370 B. Invalid Species of Chusquea 370 1 I. INTRODUCTION The bamboos (Bambusoideae) are an extremely diverse and economically Important group of grasses comprising 60-70 genera and at least 600 species (McClure, 1966; Soderstrom, personal communication, Dept. of Botany, Smithsonian Institution). In both the Asian and American tropics, the woody bamboos are one of the most visible and characteristic components of the flora. An understanding of the systematics of the Bambusoideae has grown slowly because of their unusual flowering cycles and the difficulties involved in obtaining adequate collected material. In recent years, two fine works (McClure, 1973; Calderdn and Soderstrom, 1980) have provided a more clearly defined concept of the subfamily as a whole, as well as a better understanding of generic delimitations within the American bamboos. There remains nonetheless much work to be done in refining tribal, generic and specific boundaries within the Bambusoideae. Taxonomic study of this group has been complicated by the fact that bamboos often flower only at the end of long Intervals varying among species from a few years to as many as 120 years. Although considerable variation has been observed, many species tend to have characteristic cycle lengths. At the proper time, all the individuals of a given species flower simultaneously and then die. Propagation occurs by rejuvenation of rhizomes or seedling'establishment. The mechanism whereby this cyclical flowering is controlled and maintained remains one of the great biological mysteries. Among the woody bamboos, Chusquea Kunth has long been recognized as a large and diverse genus. According to my estimate, it comprises 2 approximately 120 species, thus making it the largest genus in the Bambusoldeae. Chusquea is restricted to the New World, where it is found from Mexico through Central America, along the Andes to Chile and Argentina, and eastward into Brazil. Throughout its range it is primarily montane, but the aggregate altitudinal range of its species is from sea level to more or less 4,000 m. The majority of Chusquea species inhabit the lush, misty montane forests of Central and South America, but a few hardy members of this genus are characteristic of the high altitude Andean grasslands known as paramos. McClure (1973) segregated the high altitude species of Chusquea into a new genus, Swallenochloa. Only vegetative characters were used to separate the two genera. Both genera share multiple, Independent buds per node, solid culms becoming flstulose with age, one-flowered spikelets and a chromosome number of 2n = 40, a combination of features otherwise unique among bamboos. Clearly of chusqueold alliance, the generic status of Swallenochloa was questionable, given the heterogeneity encompassed by Chusquea. Not surprisingly, available herbarium material of Swallenochloa. and for the most part Chusquea. was poor, and neither genus had been extensively studied in the field. I undertook field and laboratory studies of these bamboos in order to determine the validity of the generic status of Swallenochloa. and thus elucidate its relationship to Chusquea. A necessary extension of this study was the investigation of other "arms of diversity" (McClure, 1973, p. 73) Included in Chusquea. Based on the evidence presented here, I have concluded that Swallenochloa forms a coherent natural group within 3 Chusquea. not a separate genus. Two other good natural groups within Chusquea, along with Swallenochloa, are formally recognized and treated as sections. It is to be hoped that this work will provide a sound basis for subsequent, much needed systematic studies in Chusquea. 4 II. MATERIALS AND METHODS A. Herbarium Studies Herbarium specimens were examined to determine distribution, phenology, and morphological variation. I thank the curators who kindly loaned specimens and types. I owe a special debt of gratitude to the Herbarium Services Unit of the U. S. National Herbarium (Smithsonian Institution), which handled the large loans of specimens and types that constituted the bulk of my herbarium loan material.