L. van der Pijl Principles of Dispersal in Higher Plants Third Revised and Expanded Edition With 30 Figures Springer-Verlag Berlin Heidelberg New York 1982 Dr. LEENDERT VAN DER PUL Emeritus Professor of Botany University ofIndonesia and University ofNijmegen Sportlaan 236 The Hague/Netherlands The cover motif shows water burrs with the double function of transport (via attachment to animals) and of establishment (anchor ing to the substrate). ISBN-13: 978-3-642-87927-2 e-ISBN-13: 978-3-642-87925-8 DOl: 10.1007/978-3-642-87925-8 Library of Congress Cataloging in Publication Data. Pijl, L. van der (Leendert van der), 1905-. Principles of dispersal in higher plants. Bibliography: p. Includes index. l. Seeds-Dispersal. 2. Botany-Ecology. 1. Title. QK929.P5 1982 582'.0467 82-848 AACR2. This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically those of translation, reprinting, re-use of illustra tions, broadcasting, reproduction by photocopying machine or similar means, and storage in data banks. Under § 54 of the German Copyright Law where copies are made for other than private use a fee is payable to "Verwertungsgesellschaft Wort", Munich. © by Springer- Verlag Berlin Heidelberg 1969, 1972 and 1982 Softcover reprint of the hardcover 3rd edition 1982 The use of registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant pro tective laws and regulations and therefore free for general use. Typesetting, printing and bookbinding: Konrad Triltsch, Graphischer Betrieb, Wtirzburg. 2131/3130-543210 Preface to the Third Edition The second edition was a hasty one, prepared in hospital only with the help of amendations on typed slips. The present revision has been more thorough, so that contents and references were almost doubled compared to the first edition. Even more emphasis has been laid on ecology (including syne cology), evolution and establishment after transport. The temptation was great to present these points under a new title, which would also have avoided being quoted with data (as being the ultimate wisdom) from the 1968 edition sitting in the local library. The publisher, though very liberal in satisfying needs, is, however, at the same time very moral and conscientious in his marketing methods, which means maintaining the original title. This though he, too, profits from selling one's "principles". I regret the time did not allow inclusion of the results of the Symposium on Dispersal and Distribution, Hamburg, 10-12 June 1981. It seems polite to react to criticisms by some reviewers: A. On the loss of readability by the numerous cross-references: The very compressed text of a textbook should be studied, not just read. An ecosystem is a web with many internal connections - and so is an ecological book, where aspects from different chapters have to be interconnected for coherence without repetition in each. B. On complaints that an author's index and a glossary are lack ing: Such an index would only be necessary in a more historically orientated review - and a glossary for terms is superfluous as the subject - index refers to definitions special to our field. The Hague, Spring 1982 L. VAN DER PIJL Preface to the First Edition The work offered here is a companion volume to the work by K. FAEGRl and L. VAN DER PUL, Principles of Pollination Ecology, which deals with the preceding phase ofreproduction in plants. In the present work too, the emphasis is on principles and ecolo gy. It is neither an enumeration of mechanisms, nor a compilation of cases. RIDLEY'S monumental work The Dispersal of Plants Through out the World comprises 700 large pages of small print, and research has proceeded since then. Though this work is more than just a compilation and contains much insight and thoughts on principles in addition to reviews, its completeness hinders its use as a textbook. As a reference work, it is unsurpassed and the writer made frequent use of it. The writer paid special attention to functional backgrounds for the use of taxonomists working with "characters" and to biosystem atics at the macro level. He is indebted to Dr. P. MULLER-SCHNEIDER (Chur, Switzer land) for the permission to translate parts of his Verbreitungsbiologie der Bliitenpjlanzen - of which permission a modest use has been made. Thanks are also due to the Director of the Rijksherbarium at Leyden, and to its librarian for the use of the library. Mr. F. J. NATAN was so kind as to take a number of photographs at the author's request. Prof. Dr. H. F. LINSKENS stimulated the work actively and made completion possible with the collaboration of the members of his staff at Nijmegen University, amongst whom Miss I. DE Roos should be thanked especially. Prof. Dr. B. J. D. MEEUSE (Seattle) was of great service, criticiz ing the manuscript. The Hague, Summer 1968 L. VAN DER PUL Contents I. Introduction . . . . . . . . . . . . . . . A. The Place of Dispersal in the Chain of Life B. Limitations and Objections . . 3 C. History and General Literature 4 II. General Terminology . . . . . . . . . . . . . . . . 6 III. The Units of Dispersal ............ 10 Vegetative Parts in Dispersal and False Vivipary 11 IV. The Relation Between Flowers, Seeds and Fruits 15 A. Seed and Fruit . . . . . . . . . . . . . 15 B. Morphological Fruit Systems . . . . . . . 16 C. Morphological Interaction Between Fruit and Flower 16 l. General. . . . . . . . . . 16 2. Position. . . . . . . . . . 18 3. Monovuly and Monospermy 19 4. Inferiority and the Calyx . . 19 D. Inadequacy of Current Fruit Terminology 20 V. Ecological Dispersal Classes, Established on the Basis of the Dispersing Agents 22 A. General. . . . . . . . 23 B. Invertebrates . . . . . 23 C. Fishes and Ichthyochory 23 D. Reptiles and Saurochory 25 E. Birds and Ornithochory 28 1. Epizoochory by Birds 28 2. Synzoochorous Bird Diaspores 29 3. Endozoochory. . . . . . 31 Non-adapted Diaspores. . . 31 Adapted Diaspores. . . . . 33 The Syndrome of Bird Diaspores 35 Oil-containing Fruits . . 38 Remarks on Evolution . 39 Mimesis (Imitative Seeds) 40 VIII Contents F. Mammals and Mammaliochory 45 l. General. ....... . 45 2. Dyszoochory and Rodents 45 3. Accidental Endozoochory . 46 4. Adaptive Endozoochory 47 Ungulates ...... . 48 Bats and Chiropterochory 49 Primates . . ... 53 Various Mammals . 54 G. Ants and Myrmecochory 55 H. Wind and Anemochory 60 l. General. ... 60 2. Dust Diaspores . . . 63 3. Balloons . . . . . . 64 4. Plumed (Comose) Diaspores 64 5. Winged Diaspores . . . . . 65 6. Tumbleweeds . . . . . . . 67 7. Wind-Ballists (Anemoballists) 69 J. Water and Hydrochory ... . 70 l. General. ........ . 70 2. Rain Wash (Ombrohydrochory) 71 3. Rain-Ballists. . . . . . . . . 72 4. Submerged Transport in Water 73 5. Floating Diaspores. . . . . . 74 K. Epizoochory, Transport on the Outside of Animals in General . . . 78 1. Diverse Origins 78 2. Trample Burrs. 79 3. Water Burrs. . 81 4. Burrs and Other Adhesives Above Ground Level 81 5. Other Spiny Fruits. . . . . . . . 82 L. Autochory, Dispersal by the Plant Itself 83 1. General. . . . 83 2. Active Ballists. . . 84 3. Passive Ballists 86 4. Creeping Diaspores 87 M. Barochory, Dispersal by Weight Only 89 N. Retrospective View . . . . . . . 90 VI. Dispersal Strategy and the Biocoenosis 91 A. Atelochory . . . 91 l. General. . . . 91 2. Synaptospermy 92 3. Basicarpy . 94 4. Geocarpy. . . 94 Contents IX B. Polychory and Attendant Phenomena 96 1. General. . . . 96 2. Heterodiaspory . . . . . . . . 98 3. Tachyspory . . . . . . . . . . 100 C. Concluding Remarks on Synecology 101 1. Deserts. . . . 10 1 2. The Rain Forest 102 3. Epiphytes. . 106 4. The Arctic . . 107 5. Island Floras . 107 6. Plant Sociology and Dispersal 112 7. Coordinated Dispersal 113 VII. Establishment 115 A. General. 115 B. Fixation . 116 C. Vivipary . 117 D. Germination 120 1. General Importance 120 2. Span of Life and Dormancy 121 3. Influence of Dispersing Agents and Other Stimuli 122 VIII. The Evolution of Dispersal Organs in General 125 A. Aims. . . . . . . . . . . . . . . . . 125 B. Isosporous Pteridophytes . . . . . . . . 125 C. Heterosporous Pteridophytes with Free Megaspores 125 D. Pteridosperms. . . . . . . . . . 128 E. Gymnosperms (or Pre-Angiosperms) 130 F. Angiosperms . . . . . . . . . . 132 1. The Seed . . . . . . . . . . . 132 2. The Seed Escaped from Angiospermy 133 3. The Sarcotesta Maintained in Conventional Fruits 135 4. Arilloids . . . . 138 5. Pulpa. . . . . . . 143 6. The Pericarp Fruit . 145 Shift of Function 145 Autonomous Cycles 147 Further Evolutionary Influences and Processes 147 IX. Ecological Developments in Leguminous Fruits 150 X. Dispersal and the Evolution of Grasses 160 A. Comparison with Cyperaceae . . 162 B. Return to Gramineae (i.e. Oryzeae) 163 C. Bam busoid Grasses . . . . . . . 166 x Contents D. Bamboos ................ . 168 E. Open Plains and Higher Grasses . . . . . . . 169 F. Some More Remarks on Awns and on Establishment 176 G. Retrospective Views . . . . . . . . . 180 XI. Man and His Plants in Relation to Dispersal 183 References. . . . . . . . . 188 Subject Index . . . . . . . 201 Index of Scientific Plant Names 206 Index of Scientific Animal Names 215 I. Introduction A. The Place of Dispersal in the Chain of Life Microbiologists' concepts are seldom concerned with dispersal and areas of dis tribution. One of their rules, sometimes indicated as "Beijerinck's law", states: everything is everywhere, but the milieu (environment) selects. In microbiologi cal terms, this means that a special substrate can demonstrate the presence, and promote the development, of certain microbes specialized for that substrate. Such lower organisms are evidently so easily spread that they are in principle not limited by the dispersal factor. Some fungi and mosses requiring special sub strates (e.g. dung) have advanced beyond this point, developing devices for directed transport of spores to preferred substrates; and in the higher plants, in which spores have lost their general function of dispersal, the same purpose is served by the microspores which are brought to the stigma. This directed trans port of microspores is dealt with in pollination ecology. In higher plants, coloniz ing dispersal is a factor limiting distribution more severely. In this book, we have to study the ways and means which the higher plants employ to reach, with their newly developed dispersal organs, sites where a new generation can be established. More specifically, this involves the methods used to keep their descendants separated in space and to provide each with its own site, where it can compete with other plants; it also concerns the methods em ployed to defend the future of the species by exploring new territories, par ticularly following climatic fluctuations, or conversely to maintain a foothold on a favourable site. Another feature of spores, the power to withstand and survive unfavourable conditions over a long timespan, is also evident in the reproductive organs of higher plants. The products of these organs, such as seeds, may combine the ad vantages of dormancy with those of genetic variation, in contrast to vegetative resting organs, which merely continue the life of the individual without hope for the future of the species in a changing environment. In the present study, we shall have the opportunity to emphasize two dif ferent aspects, viz. actual dispersal as studied in the field, and the structural basis needed to attain this dispersal; both will be considered in an ecological context. All too often, the second aspect has predominated so strongly in works on dis persal that they remain examples of herbarium ecology, or worse, writing-desk ecology. Nevertheless, the structural aspect cannot be dismissed as the starting point, the more so since a mere enumeration of findings in certain sites (as by Heintze, 1932) produces an unmanageable chaos.