Guayule (Parthenium Argentatum Gray)
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GUAYULE (PARTHENIUM ARGENTATUM GRAY) A RUBBER-PLANT OF THE CHIHUAHUAN DESERT BY FRANCIS ERNEST LLOYD Professor of Plant Physiology, Alabama Polytechnic Institute WASHINGTON, D. C. SB PUBLISHED BY THE CARNEGIE INSTITUTION OF WASHINGTON 291 .G8L56X 1942 GUAYULE (PARTHENIUM ARGENTATUM GRAY) A RUBBER-PLANT OF THE CHIHUAHUAN DESERT BY FRANCIS ERNEST LLOYD Professor of Plant Physiology, Alabama Polytechnic Institute WASHINGTON, D. d PUBLISHED BY THE CARNEGIE INSTITUTION OF WASHINGTON 191 I CARNEGIE INSTITUTION OF WASHINGTON PUBLICATION NO. 139 Copies of this Book were first issued JUL271911 Reproduced by Lithograph May 1942 PRESS OF J. a L1PP1NCOTT COMPANY PHILADELPHIA, PA. PREFACE. In 1907 the author of the present paper was engaged by the Continental-Mexican Rubber Company and the Intercontinental Rub- ber Company to organize investigations looking toward the successful cultivation of a Mexican desert rubber plant, the guayule (Parthenium argentatum Gray). Dr. Theodore Whittelsey and Dr. J. E. Kirkwood later became identified with this undertaking, the former as chemist, the latter as assistant botanist. The headquarters for the investiga- tions were established at the Hacienda de Cedros, Partido de Mazapil* 2acatecas, Mexico. It was not a matter for congratulation that, at the close of a year, the directors found it inadvisable, for financial reasons consequent on the panic of 1907, to continue the department of inves- tigation. By the courtesy of the company, however, the author carried on his studies for some three months beyond the termination of his business relations with it, and this period, falling during the growing season of 1908, brought to light many important facts. Still further observations of capital importance, in part -on experiments begun in 1907 and 1908, were made by the writer in April 1909, while represent- ing the United States Rubber Company, a commission which could not have been prosecuted without the kind concurrence of President C. C, Thach and a number of the writer's colleagues at the Alabama Polytech- nic Institute. As silence was not imposed by the United States Rubber Company, it has been possible to include these observations. No less than hearty recognition is due also to Mr. W. H. Stayton, formerly captain, U. S. Navy, sometime president of the Continental- Mexican Rubber Company, and now president of the Texas Rubber Company. It is stating an open secret to say that it was through the initiative and enthusiasm of this gentleman that the work of the inves- tigation was undertaken and would have been continued but for cir- cumstances beyond his control. Mr. Stayton has shown a liberal and scientific'spirit, qualities not of necessity nor at all times associated. Thanks are due further to Prof. J. C. Arthur and Prof. W. G, Far- low for reports on various pathological matters; to Dr. M. T. Cook for contributing manuscript on the galls found on guayule; to Dr. A. D. Hopkins for a report on the guayule bark-borer; to Dr. L. 0. Howard and Dr. J. G. Sanders for the identification of certain insects; and to Prof. B. L. Robinson for his courtesy in causing a photograph of the type speci- men of guayule to be made. Mr. Charles S. Ridgway has rendered sub- stantial aid in the preparation of certain figures. The drawing for figure 5 was supplied by Professor Arthur; the nega- tive of plate 2, fig. B, was made by Dr. W. E. Hinds; Professor Trelease furnished the illustration (fig. 4) and description of the Cedros sotol, and kindly made several other determinations; the negatives of plate 3 and D iv Preface. plate 4, fig. A, were made by Mr. Victor Blanco. Dr. H. van der Linde obtained for me valuable material of irrigated plants from Caopas. Dr. Theo. Holm has afforded me the benefit of his criticism of the portion of this work treating of the anatomy, and has been good enough to examine inaccessible literature for me. Dr. W. E. Safford did a like service regarding a few pages in the first chapter. To Prof. W. L. Bray I am indebted for information about the Texas guayule fields, later verified by me personally; and to my colleagues, Prof. C. L. Hare and Prof. J. P. C. Southall, for assistance in making chemical analyses and for mathematical formulae, respectively. With reference to the chapters which follow, no pretensions are made with regard to completeness. The exhaustive study of a single plant from all points of view might well be numbered among the labors of fable. The reader is asked also to remember that the study of but a single growing-period was possible. Much of the experimentation, therefore, was done, as it eventually turned out, during the most un- favorable season; but in the case of field experiments this was not entirely a misfortune. That the theoretical bearing of many observa- tions and more refined methods of making them are less attended to than the matter warrants has been due to the urgent necessity of practical success. With these qualifications, the work may be regarded as a report on a unique opportunity, unhappily shortly terminated, to bring a hitherto feral desert plant under the subjugation of culture. That suc- cess may ultimately be attained is not an unreasonable nor an unwar- ranted expectation, for which statement the interested reader will find not a little evidence in what follows. FRANCIS ERNEST LLOYD. ALABAMA POLYTECHNIC INSTITUTE, January 1910. TABLE OF CONTENTS. Page. Preface iii List of plates ' vii CHAPTER I.—HISTORICAL ACCOUNT. Original discovery and description 3 The vulgar name 4 Primitive and later uses ] 5 History of manufacture. 7 Methods of extraction 8 The natural supply of shrub 10 Attempts at culture 1 a CHAPTER II.—THE ENVIRONMENT. Geographical distribution 13 Altitudinal distribution 13 Climate 14 Rainfall 14 Air-temperatures 15 Soil-temperatures 18 Soil-moisture 19 Relation of rainfall and temperature to growth 20 Relative humidity 21 Topography and soil 23 Density of growth 25 Bibtic relations 35 CHAPTER III.—DESCRIPTION OF THE GUAYULE. Seed 46 Seedling. 48 The mature plant 50 Root-system * 50 Retofios , 51 Method of branching 54 Biotypes 55 Size 56 Surface characters of the stem and method of determining age 57 Field plants 57 Irrigated plants * .. 58 The leaves ... 58 The inflorescence and the flowering period 59 The production of seed 60 CHAPTER IV.—REPRODUCTION. Methods of reproduction , - 61 Retofios, normal and induced : 6x Seed 68 Rate of reproduction and of growth. ^ 75 Rate of growth during germination. 75 Rate of growth in maturer plants beyond the seedling stage 79 Rate of growth in terms of stem-length 79 Rate of growth in earlier years after germination 79 Rate of growth in medium-sized plants 81 Rate of growth in irrigated plants. ,.,.. ... 84 Field plants 85 CHAPTER V.—AKATOXT AND HISTOLOG*. Root • 90 Primary structure , ,« .. ,\ ,. 90 Secondary structure. 90 Hypocotyl , ,.,.....- .,.. 96 Primary structure •.,..«•.. 96 Secondary structure *.... 99 Later secondary structure.. ,. ..,.,. IOX vi Table of Contents. CHAPTER V.—ANATOMY AND HISTOLOGY—Continued. Page. Age and structure in the seedling 104 ticotyl 105 e definitive stem 107 Primary structure 107 Secondary structure 109 Origin of the medullary and cortical stereome no Annular structure .......... 114 The effect of abundant water upon anatomical structure 116 Relative volumes of cortex and wood 117 Effect of various amounts of water of irrigation 121 Effect of drought following irrigation 122 Effect of irrigation on the physical characters of the wood 122 The peduncle 124 The leaf 125 Cotyledons. 125 Prophylls 126 The definitive leaf , 126 CHAPTER VI.—THE RESIN-CANALS IN THE GUAYULE. The canal-systems .. 165 Primary canals in the root and hypocotyl 165 Primary cortical canals „ . 166 Medullary canals ' > 169 The canals in the leaf 171 jPrimary canals in branches. 171 Secondary canals In root, hypocotyl, and stem 172 Canals in the peduncle.._.,> 172 The canals In retonos 173 The contents of the canals; their origin 174 The role' of resin.. .• « 174 Resin-content of guayule by analysis : 175 CHAPTER VII.—THE ORIGIN AND OCCURRENCE OF RUBBER. Methods. 176 General distribution of rubber in the plant 177 The appearance of rubber in richly loaded tissues..•., . 179 Behavior of peridermal divisions toward rubber 179 The development of rubber In the cell 180 Centers of secretion * 181 Rate of rubber secretion relative to growth.., 183 Rubber-content by chemical methods. 185 Variation In relative amount of rubber in field plants...................... 187 Relation of rubber and resin. .............................. 188 The significance of rubber......... 188 Summary. .* 190 CHAPTER VIII.-—VEGETATIVE REPRODUCTION. Induced root-regeneration. 193 Propagation by cuttings. 195 CHAPTER IX.—THE CULTIVATION OF GUAYULE. Forestal operations. 199 Present field operations. ........................................... x99 Suggested rules of practice,........................................ 200 Harvesting period.............. 202 Reseedlng barren ground,......................... 202 Cultural operations.................................................... 203 Seed 203 The raising of seedlings. 203 Irrigation.;....................................................,. 208 Transplanting.................................................... 209 H&rvestlag cultivated guayole...................................... 21© Catch crops, ...................................................... 210 Bibliography ........................................................... 211 Plates 1-21 and 40-46 are not included in the