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Durham E-Theses Studies in the genus gymnocalycium Swales, G.J How to cite: Swales, G.J (1975) Studies in the genus gymnocalycium, Durham theses, Durham University. Available at Durham E-Theses Online: http://etheses.dur.ac.uk/8889/ Use policy The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that: • a full bibliographic reference is made to the original source • a link is made to the metadata record in Durham E-Theses • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. Please consult the full Durham E-Theses policy for further details. Academic Support Oce, Durham University, University Oce, Old Elvet, Durham DH1 3HP e-mail: [email protected] Tel: +44 0191 334 6107 http://etheses.dur.ac.uk STUDIES IN THE GENUS GYMNOCALYCIUM G. J. SWALES The copyright of this thesis rests with the author. No quotation from it should be published without his prior written consent and information derived from it should be acknowledged. A Thesis submitted for the degree of Master of Science in the University of Durham September 1975 1 Studies in the genus GYMNOCALYCIUM Pfeiffer A critical survey of the literature, especially original descriptions, of two of the major groups within the genus; an attempt to define the distribution of these species as far as it is known; a tentative suggestion for a better regrouping of the species, and photographs, where available, of examples from these groups at present in cultivation in my reference collection. IA ABSTRACT During a preliminary survey of seed structure within the genus Gymnocalyoium it became obvious that in the English language at least, there was no authoritative description of many of the plant species concerned. Consequently, a critical literature survey, with particular attention to the original descriptions has now been carried out for the 51 species of Gymnocalycium generally referred to the Macrosemineae and the Ovatisemineae, two of the original five seed groups of Fric and Kreuzinger. At the same time, the majority of the species concerned have been kept for a number of years in cultivation in the author's reference collection. The study of the living plants, combined with the results of the literature survey, has led to what is hoped to be a much clearer concept of the various species, and, as a prelude to further study, a tentative scheme is put forward showing possible inter-relationships and evolutionary trends within the combined groups. ie> CONTENTS Page Prologue IB Introduction 2 The genus Gymnocalyoium 7 The sub-division of the genus by means of seed characteristics 11 Illustrations of the seed groups 14 Groups 1 & 2 of Prift and Kreuzinger sub-divided 15 Group A 16 G. leeanum 18 G. netrelianum 25 Group B 30 G. artigas 31 G. guerkeanum 40 G. uruguayense 46 Group C 55 G. hyptiacanthum 57 G. schroederianum 66 G. deeszianum 74 Group D 79 G. platense 80 G. striglianum 88 G. gibbosum 90 G. chubutense 122 G. brachypetalum 131 Group E 136 G. andreae 137 G. baldianum 146 G. uebelmannianum l6l JC CONTENTS (oont..) Page Group F l6^ G. leptanthum 165 G. capillaense 169 G. slgelianum 173 G. sutterianum 177 The G. capillaense, G. slgellanum, and G. sutterianum complex 182 Group G 190 G. calochlorum 191 Group H 201 G. bruchii 202 G. alblsplnum 222 Group I 226 G. fleischerianum 227 G. paraguayense 238 G. megalothelos 249 Group J 256 G. denudatum 257 G. horstll 279 Two species of doubtful identity 285 G. hamatum 286 G. stuckertii 289 Conclusion 302 Epilogue 314 Acknowledgements 315 It) PROLOGUE "First of all I had to familiarise myself with the literature of the subject, and then compare the plants that I had found in the country-side with the pictures in the books; then, when I found any similarity between them, I had to study the descriptions more closely. After a time, I acquired skill from practice; when I chanced upon some unknown plant, I first considered to what tribe and family it belonged or could be assigned ... so I first of all looked for it in the appropriate group, and in this way saved myself a great deal of trouble." John Ray: Catalogus Plantarum circa Cantabrigiam nascentium. 1660. (Ewen & Prime's Translation 1975) 2 Introduction ]||||m^ally, the Cactaceae is probably one of the most neglected families of fxowering plants and yet it contains a wealth of interesting and unusual material, and. even today, new taxa are still being added to its ranks. My own interest in the family dates from over twenty years ago, and by the time my collection of plants had outgrown its original window- sill, it was already becoming obvious to me that relatively little was known about them. Reference books were hard to find and those few which were available often contradicted each other, and the position was obviously a most unsatisfactory one. Of virtually no economic value, it is largely through the activities of commercial interests supplying the fluctuating demands of small numbers of amateur enthusiasts throughout the world over the past 150 years that our knowledge of these plants has gradually increased. Unfortunately, there are fashions in cactus collecting as in everything else and certain genera have, in the past, become popular and as a result have been heavily collected in habitat, only to be neglected later in favour of some other genus. In addition, large growing species unsuitable for greenhouse cultiva• tion have been generally ignored. Thus our knowledge of the group tends to be somewhat fragmentary. Due to competition between commercial collectors in the field, habitat details are sometimes jealously guarded secrets and so our knowledge of distribution too, in many cases, is vague or almost non-existent. The taxonomy of the group has also suffered. Many amateurs uncritically tend to amass labels rather than plants, so that commercial suppliers find it difficult to resist the temptation to create new varieties and species on the flimsiest of evidence from amongst the admittedly often 3 very variable material which they receive from habitat. Consequently, from the taxonomic view-point, there is a great deal of work which needs to be done to place the whole system of nomenclature on a firm scientific footing. As international trade got back to normal after the 1939-^5 war, the supply of cactus plants available to the amateur increased greatly and in order to compromise with limited greenhouse space and expensive heating, many collectors began to specialise and in my own case, more by chance than anything else, I decided to concentrate on the genus Gymnocalycium. Very few, if any, of the species seemed to be regarded as rarities or difficult in cultivation and thus material was available at a reasonable price. As the size of the collection increased, so did my dissatisfaction with the nomenclature. If I remember correctly, it was Schutz's first article on the sub-division of the genus utilising the characteristics of the seeds, published in 19^2, which finally stimulated me to take up the detailed study of the plants that I was collecting. It appeared that Frifi and Kreuzinger in 1935 had begun the process by a simple division into five groups, but although initially this served a useful purpose, with the increase in the number of known species, one group at least became increasingly unwieldy and was obviously heterogeneous in nature. Schiitz developed the classification further but still more work was needed before a satisfactory division could be established, and only a few improvements resulted from his second publication in 1968. When I had pursued my study here described for nearly a year, Buxbaum in 1968, published his own revision of the seed classification. He made a number of the modifications I had intended to propose, but also left several anomalies which in my opinion needed further study. 4 By this time, it had become apparent to me that one of the major problems was getting seed which was reliably named, for much confusion had been caused by wrongly named or hybrid seed. In addition, it was found that, for certain species, there was considerable difference of opinion as to what the plants should really look like. The original descriptions in many cases were not easily available and the majority were in German, Spanish, Czech, French and Dutch journals, and though they included, for the most part, a diagnosis in Botanical Latin, many popular authors copied from secondary publications, and were not always reliable. Further complications arose from the fact that many so-called authorities who had written widely in various journals over the years were in fact, collectors of plants rather than students of Botany, and although they were most knowledgeable in some respects, they were sometimes sadly ignorant in others. In fairness to the amateurs, however, it must be recorded that the professionals were not entirely blameless. For example, it is said of Spegazzini, whose name is connected with almost every aspect of Argentinian botany, not only the study of the Cactaceae, that he "generally made notes on the spot or from the plants cultivated in his house from flower pots without labels. His memory was not always so reliable as to recollect the name itself and the place of origin of each specimen. ... Spegazzini did not preserve at all the specimens of the Cactaceae used in his studies, which in several cases created synonyms of his own species or amplified geographical distributions with analogous species all attributed to one alone through mistaken determination on the ground." (Castellanos, writing in the American Cactus & Succulent Journal, 1940.) 5 Over and above these problems, one has to contend with the large numbers of European grown plants, often of very doubtful parentage, which in recent years have flooded the market in response to the increasing interest taken by the general public in Cacti as house plants.