Principles of Dispersal in Higher Plants

170 Pages·1972·4.429 MB·English

by  Dr. Leendert van der Pijl (auth.)

L. van der PijI
Principles of Dispersal
in Higher Plants
Second Edition
With 26 Figures
Springer-Verlag
New York· Heidelberg. Berlin 1972
Dr. LEENDERT VAN DER PIJL, emeritus Professor of Botany, University
of Indonesia, Professor at the University of Nijmegen.
Sportlaan 236, The Hague/Netherlands
ISBN-13: 978-3-642-96110-6 e-ISBN-13: 978-3-642-96108-3
DOl: 10.1007/978-3-642-96108-3
This work is subject to copyright. All rights are reserved, whether the whole or
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@ by Springer-Verlag Berlin Heidelberg 1969 and 1972. Library of Congress
Catalog Card Number 72-83445.
Softcover reprint of the hardcover 2nd edition 1972
The use of general descriptive names, trade marks, etc. in this publication, even
if the former are not especially identified, is not be taken a. a sign that suth
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Preface to the Second Edition
Reviewers from diverse branches of botany have exerted pressure to have
chapters dealing with their field extended. If only to cover his incompetence, the
author could not accede to these requests. Nor was it possible to respond to
Eastern European urgings to extend the classificatory terminology, especially in
ChapterX.
He is grateful for indications of factual shortcomings in the chosen field,
especially for those by Dr. RUDOLF SCHMID (Ann Arbor), who provided exten
sive comment.
The Hague, spring 1972 L. VAN DER PIlL
Preface to the First Edition
The work offered here is a companion volume to the work by K. FAEGRI and
1. VAN DER PIJL, Principles of Pollination Ecology, whim. deals with the preced
ing phase of reproduction in plants.
In the present work too, the emphasis is on principles and ecology. It is
neither an enumeration of mechanisms, nor a compilation of cases. RIDLEY'S
monumental work The Dispersal of Plants Throughout 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 text
book. 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 biosystematics at the macro-level.
He is indebted to Dr. P. MULLER-SCHNEIDER (Chur, Switzerland) for the
permission to translate parts of his Verbreitungsbiologie der Blutenp/lanzen - of
whim. 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 Uni
versity, amongst whom Miss I. DE Roos should be thanked especially.
Prof. Dr. B. J. D. MEEUSE (Seattle) was of great service, criticizing the
manuscript.
The Hague, summer 1968 L. VAN DER PIJL
Contents
I. Introduction . • • • • • • • . . • . 1
A. The Place of Dispersal in the Chain of Life 1
B. Limitations and Objections • • 2
C. History and General Literature 4
II. General Terminology • 6
III. The Units of Dispersal . 9
Vegetative Parts in Dispersal and False Vivipary 9
IV. The Relation between Flowers, Seeds and Fruits. 13
A. Seed and Fruit . • . • . . . . . . . 13
B. Morphological Fruit Systems . • . . . . 14
C. Morphological Interaction between Fruit and Flower 14
1. General. . . • • • • . 14
2. Position. . . . • . • • 15
3. Monovuly and Monospermy • 16
4. Inferiority and the Calyx 17
D. Inadequacy of Current Fruit Terminology. 17
V. Ecological Dispersal Classes, Established on the Basis of the Dispersing
Agents . • . 19
A. General. . . . . . 19
B. Invertebrates • . . • 19
C. Fishes and Idlthyochory 20
D. Reptiles and Saurochory . 21
E. Birds and Ornithochory . 24
1. Epizoochory by Birds. 24
2. Synzoochorous Bird Diaspores 25
3. Endozoochory . . . . 27
a) Non-adapted Diaspores . 27
b) Adapted Diaspores. . . 29
c) The Syndrome of Bird Diaspores . 30
d) Oil-containing Fruits. . 32
e) Remarks on Evolution . 33
f) Mimesis (Imitative Seeds) 33
F. Mammals and Mammaliochory . 39
1. General. . . • . . • 39
2. Dyszoochory and Rodents 39
3. Accidental Endozoochory . 40
4. Adaptive Endozoochory . 40
Ungulates. • . . . 41
Bats and Chiropterochory 42
x
Contents
Primates . • . 46
Various Mammals 46
G. Ants and Myrmecochory 47
H. Wind and Anemochory 52
1. General. • . 52
2. Dust Diaspores • • 55
3. Balloons • • • . 55
4. Plumed (Comose) Diaspores • 55
5. Winged Diaspores • • . . 56
6. Tumbleweeds. • • . • • 58
7. Wind-BaUists (Anemoballists) 60
J. Water and Hydrochory • • . 60
1. General. . • • • • . . 60
2. Rain Wash (Ombrohydrochory) 62
3. Rain-Ballists • • • . • . • 62
4. Submerged Transport in Water. 63
5. Floating Diaspores. . • . . 64
K. Epizoochory, Transport on the Outside of Animals in General . 67
1. Diverse Origins • 67
2. Trample Burrs 68
3. Water Burrs • • 68
4. Burrs . • • • 69
5. Other Spiny Fruits • 70
L. Autochory, Dispersal by the Plant Itself 70
1. General. • • 70
2. Active Ballists 71
3. Passive Ballists 73
4. Creeping Diaspores . 74
M. Barochory, Dispersal by Weight Only 76
VI. Combination, Limitation and Cooperation . 78
A. Atelochory. • • 78
1. General. • • 78
2. Synaptospermy 79
3. Basicarpy . • 80
4. Geocarpy . • 80
B. Polychory and Attendant Phenomena 82
1. General. •• • • • • 82
2. Heterodiaspory • • . • . . 83
3. Tachyspory . . . . • . . 85
C. Concluding Remarks on Synecology 86
1. Deserts • • • . 86
2. The Rain Forest . 87
3. Epiphytes . . • 90
4. Island Floras. • 90
5. Plant Sociology and Dispersal 94
6. Coordinated Dispersal. • • 95
Contents XI
VII. Establishment , , , , 97
A. General 97
B. Fixation 97
C. Vivipary 98
D Germination 101
1. General Importance 101
2. Span of Life and Dormancy 102
3. Influence of Dispersing Agents and Other Stimuli 103
VIII. The Evolution of Dispersal Organs 105
A. Aims ••••••••• 105
B. Isosporous Pteridophytes. • • 105
C. Heterosporous Pteridophytes with Free Megaspores . 105
D. Pteridosperms • • • • • . • • 108
E. Gymnosperms (or Pre-Angiosperms) • 110
F. Angiosperms . • • • • • • • • 111
1. The Seed ••••••••. 111
2. The Seed Escaped from Angiospermy 112
3. The Sarcotesta Maintained in Real Fruits 114
4. Arilloids • • • • 116
5. Pulpa .•.••• 121
6. The Pericarp Fruit. • 122
Shift of Functions • 122
Autonomous Cycles 123
Further Evolutionary Influences and Processes 124
IX. Ecological Developments in Leguminous Fruits 126
X. Mand and his Plants in Relation to Dispersal . 135
References • • • . • • . • 140
Subject Index • • . . . • . 149
Index of Scientific Plant Names. 154
Index of Scientific Animal Names 162
I. Introduction
A. The Place of Dispersal in the Chain of Life
Microbiologists' concepts are seldom concerned with dispersal and areas of distri
bution. One of their rules, sometimes indicated as "Beijerinck's law", states:
everything is everywhere, but the milieu (environment) selects. In microbiological
terms, this means that a special substrate can demonstrate the presence, and pro
mote 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 substrates
(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 transport of
microspores is dealt with in pollination ecology. In higher plants, colonizing
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
employed to defend the future of the species by exploring new territories, parti
cularly 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 time-span, 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 differ
ent 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 start
ing point, the more so since a mere enumeration of findings in certain sites (as
by HEINTZE, 1932) produces an unmanageable chaos.
2 Introduction
We must be aware of the fact that dispersal is but one link in the continuity
of life on earth, which is perpetual colonization. It starts with presentation of the
dispersal units (including dehiscence and detachment), if possible at the right
time and place, as a preparation for dispersal. This preparation also makes travel
possible by providing physiological and structural protective devices. After
travel comes settlement, not always by mere deposition, and germination. Only
then does the question arise of a substrate suitable for establishment. We shall
discuss dehiscence and its mechanisms only incidentally, viz., when they are con
nected with special ecological factors.
Any of these parts of the whole phenomenon can be the bottleneck, and in a
plant community any of them can be dominant. As the various aspects of the
overall process are also reflected in the structure of dispersal units (outside mere
dispersal function), there is all the more reason to study them. Sometimes anti
dispersal mechanisms are important for homeostasis.
We shall see in detail in Chapters VI and VII, and elsewhere, how unsound
it is, biologically speaking, to limit our attention to mere transport. All aspects
intermingle and may change in importance during succession and evolution, so
that in the dispersal organs we shall find traits relating to other spheres of life.
We shall try to keep these various features apart.
I shall often avoid the trodden path of temperate ecology and refer to tropi
cal phenomena, in the first place to be more universal, but also to be more funda
mental, since the impoverished temperate conditions, which prevail for certain
herbs and pioneer plants in temperate regions, are not truly representative.
It is also necessary to point out here provisionally that in seed plants the
dispersal organs arise ontogenetically out of so~called sexual organs, the flowers,
and therefore still manifest properties of the latter (see p. 15). When coining
terms, it will prove important to reckon with these remnant conditions.
The general effects of seed dispersal, discussed before, should be augmented
by a newer aspect. Next to pollen transport, seed dispersal is the most important
single factor promoting the gene flow in populations. GRANT (1958), for instance,
has pointed to the effect of good dispersal on variability in populations of Juni
perus in contrast to the situation in Cupressus species. EHRLICH and RAVEN
(1969) neglected this factor entirely when stating that pollen rarely has a long
range transport and that gene flow is therefore less important than is generally
thought. JANZEN (1970) emphasized for tropical seeds the importance of distan
tiation from breeding places of seed-predating insects, a special aspect of the
separation from the mother plants mentioned before.
B. Limitations and Objections
Just as was the case with pollination ecology (cf. FAEGRI and VAN DER PIlL,
1966), dispersal ecology fell into discredit in the twentieth century for being
partly the writing-desk ecology mentioned above. Many nineteenth century