F Halle R. A. A. Oldeman :P. B.Tomlinson Tropical Trees and Forests An Architectural Analysis With III Figures Springer-Verlag Berlin Heidelberg New York 1978 Prof. Dr. FRAl\C!S HALL! Institut Botanique, U11lversité des Sciences et Techniques du Languedoc 5, Rue Auguste-Broussonet, F-34000 Montpellier Prof. Dr. ROE LOF A.A. OLDI\1A1'i .. Hinkeloord ", Vakgroep Bosteelt Generaal Foulkesweg 64, NL-6703 BV Wageningen (formerly: O.R.S.T.O.M., Apartado 99-B, QUItO) Prof. Dr. PHILIP B. TOMLINso:\ Harvard University, Harvard Forest Petersham, Mass. 01366, USA ISBN 3-540-08494-0 Springer-Verlag Berlin Heidelberg New York ISBN 0-387-08494-0 Springer-Verlag New York Heidelberg Berlin Library 01' Congress Cataloging in Publication Data. HALÜ, FRANCIS. Tropical lrees and I·orests. 8iblil)graphy: p. Includes indexes. 1. Trees - Tropies. 2. Forest nora - Tropies. .1. Trees - Morphology. 4. Trees - Growth. 5. Plant morpho- gcnesis. 1. OLllE\tA'. R.AA., joint author. Il. TOMI.INSON, P.B., 19.12-. joint author. III Title. QK49.1.5.H.16 5R2'.16'0913 77-]51 ]2. This work is subject to copyright. Ali rights are reserved. whcther the whole or part of the materia] is eoncerned, specifieally those of translation, reprintmg. re-use of illustrations. broadcasting, reproduction by photocopying machine or similar means. and st orage in data banks. Under ~ 54 of the German Copyright Law where copies are made for other than private use, a fee is payable to the publisher, the amount of the fee Lü be determined by agreement with the pu blisher. \( by Springer- Ver]ag Ber]in . Heidelberg 1978. Printed in Germany. The usc of rcgistercd names. trademarks, etc. in this publication does not imp]y, l'ven in the absence of a specifie statement, that sueh names arc exempt l'rom the relevant proteetive laws and regulations and therefore free for gcneral use. Reproduction of the figures: (,ustay Dreher GmbH, Stuttgart. Typesctting, printing and bookbinding: Univcrsitiitsdruckerei H. Stürtz AG, Würzburg. 21.11(3130-543210. Jadis 11'.1' a 1'171'1'.1' étail'Ilt dl's Xc/l.I' comml' nous mais plus solidl's plus hcurcux plus amourcux pl'lIt-être plus sagl'S c'est tout J, PRÉVERT Gl'daagde, hodem1'aste hoschXl'lIootell hoomell dic 'k, Il'el vichtig jarclI lallg boom ll'ete,' en, ::00 hoogc ais nu geschotclI gcien l7('hhe, op ::00 menig !rande/gang lI'{lt 171'11 ik, arl1/l' mil'rl', u hijgl'Il'kl'II dil' .l'ta l'Il li aallsc!tOlIH'I', 0 !toogl' hooml'lIrl'kl'lI GUI\)O GEZELLE, "Ei'IIH'i'/ingi'n" Botall.\' IIl'l'ds Iwlp ./i'om thl' tmpics,' its hig plants ll'il/ l'nXl'nc!l'r hiX thinkinx E.J,H, CORNER Preface This book is not an exhaustive survey of known information in the manner of a text-book - the subject is much too big for this to be possible in a relatively concise volume- but presents a point of view. We are concerned ultimately with the analysis of tropical ecosystems, mainly forests, in terms of their constituent units, the individual trees. Many different approaches are possible in the analysis of tropical forests. A simple one is to treat the trees as obstacles which in a military sense intercept projectiles or are a hin- drance to foot soldiers (AOOOR et al., 1970). A similar ap- proach might be adopted by an engineer confronted by a forest which has to be removed to permit road construc- tion. The timber merchant is concerned with the ability of a forest to yield saleable lumber. The interest here is in the size of the larger trunks with sorne concern for the kinds of trees. At a less destructive level the scientist ai ms to compre- hend the forest from many different points of view. The forester himself, in conjunction with the taxonomist, will wish to analyze the floristic composition of the forest and perhaps account for species diversity in an evolutionary time scale (e.g., FEDOROV, 1966; ASHTON, 1969). The evolu- tionary biologist in his turn may be concerned with repro- ductive strategies in forest trees (e.g., BAWA, 1974), espe- cially in a comparative way. The approach adopted by the ecologist offers the greatest scope, since he may combine several different methods of analysis. Much research has gone into the physiognomy of tropical forests, size distribution of trees, stratification, diversity in relation to soil type or soil moi sture content and has been summarized recently by ROLLET (1974). Phenological studies of tropical forests have produced a great deal of data which reveals the extent to which flower- ing, fruiting and leaf faU may or mal' not be seasonal (e.g., COSTER, 1923; HOL TTUM, 1940, 1953; cf. also LIETH, 1970). The production ecologist is interested in the forest as an VIII Preface efficient system for Iight interception and yield of dry mat- ter, both in a relative and a comparative way (e.g., KIRA, 1978; KIRA et al., 1964, 1969; MONSI et al., 1973; 8ERNARD- REVERSAT, 1975). Photosynthetic efficiency in terms initially of leaf and branch orientation but ultimately in competitive ability is another stimulating approach which is summarized in the description of trees as "crafty green strategists" (HORN, 1971). A universal tendency in these approaches is to treat trees as equivalent units- as taxonomie, physiological, reproduc- tive units and so on. Much less attention has been given to the trees in the forest as individua1s. This is our approach. However, we do not merely regard trees as individuals at one point in time, but as genetically diverse, developing, changing individuals, which respond in various ways to fluctuations in c1imate and microclimate, the incidence of insects, fungal and other parasites but particularly to changes in surrounding trees. The tree is then seen as an active, adaptable unit and the forest is made up of a vast number of such units interacting with each other. In order to understand the adaptive strategies of the tree in the forest we must first, in a rather paradoxical way, remove it from its natural habitat and study it in isolation, more or 1ess free from the natural accidents to which it is otherwise subjected in a competitive environ ment. lso- lated in this way one can study the tree from the point of view of the geneticist and deve10pmental morphologist. The tree deve10ps from a seed which carries the genetic information which will determine its form. It is only by studying the form of the tree expressed in a more or less optimal environment that its genetic potential is clearly revealed. Briefly, we find out what the tree can "do ". This leads, therefore, to the recognition of what has been termed the" architecture" of the tree (HALLÉ and OLDEMAN, 1970), a concept which is elaborated in great detail in this book. The concept of architecture involves the idea of l'orm, impli- citly containing also the history of such a form. The life- long succession of developing l'orms in a plant is revealed by the concept of the architectural model and its reiteration. By examining large numbers of species in a comparative way, we are led to the recognition of the existence of similar developmental plans among taxonomically dissimilar trees. Much of this book is, therel'ore, a description of these Preface IX developmental "models" as established by HALLÉ and OL- DEMAN, and this provides a framework to which we can attach a great deal of information about the growth of trees in the tropics. Recognition of the existence of similar constructional principles (architectural models) in a great varicty of trees (and our survey has bcen as cosmopolitan as we could make it) implies that the" strategy" of a tree differs l'rom species to species. What significance, in fact, does architecture ha ve for the success of the tree in a natllral environment? Here we must return to the forest, away l'rom our opti- malized environment which has been so productive of new information. We have learned how a tree is capable of growing, by vi l'tue of its genetic make-up. Now we can ask the question, how, in fact, does it grow in the vigorously competitive environment of the forest itself? This leads to the recognition of ways in which a "real" tree is constructed in a natural sùessed environment. as distinct l'rom an ., ideal" tree, growing precisely according to its genetic plan and not subject to environ mental stress. This is not to suggest that we are making a distinction between theoretical and practical information. Both circllmstances exist, and trces function in both optimal and nonoptimal environments. The point will become clcarly established that without a knowledge of the potential growth activity of the tree, it is impossible to recognize its actllal growth expression. Once this is appreciated we are in a position to rcassemble the living forest in terms of its developing units. From this it should be appreciated that our approach is a biological one in the purest sense. Throughout the text we have stressed tropical examples and our ultimate aim has been to understand trees of the lowland, humid tropics. What is the reason for this em- phasis? The answer is really quite simple. Taken in a very general sense the climate of the wet tropics is uniformly favorable for plant growth and allows the existence of an enormous species diversity. Consequently in this environ- ment there is a wider array of growth expressions in woody plants than anywhere else in the world. If one seeks funda- mental principles, it is clear that one should do so where they are l'l'cely and clearly expressed. Once an llnderstanding of growth processes in tropical trees has been established, it then becomes possible to look at forests in the more x Preface constralntng environments of temperate latitudes, where diversity is less and is directed towards survival amidst macroclimatic stress. One can understand a temperate forest better when one has grasped principles of tree growth in the tropics, but scarcely the reverse. Unfortunately, botanical history has inverted this logical sequence. Consequently a degree of justification for our approach has to be introduced via our initial thumb-nail sketch of the floristic diversity of the tropics. For the same reason we have attempted to provide sorne background in morphogenetic terms for our subsequent analysis of tree architecture, since our approach is often different from that of a temperate forester for whom responses to seasonal climates seem so important in tree growth. This is by no means intended as a complete review of organogenesis in woody plants of the tropics, but it should serve to clarify further our point of view. Frequently, of course, a topic can only be discussed with examples of temperate tree species in mind because no information is available about tropical species. Our greatest problem, and one which is encountered by ail who have tried to describe tropical vegetation to an audience which has never visited it, is that the majority of plants are likely to be unfamiliar to the reader. We have used examples of common or commercially valuable trees, where appropriate, especially in the introductory chapters. We have otherwise made frequent reference to existing accounts of the more common tropical species, and to the earlier account of HALLÉ and OLDEMAN (1970), but in order that this book may carry as much new informa- tion as possible most of the illustrated examples are new. If the reader still retains a sense of the monstrous, the fabulous or the unreal in using this book he should try to make a mental reversai of the situation, which is botani- cally more appropria te. How strange is the temperate tree, leafless for a large part of the year, with such marked synchrony in its development, its brief period of extension growth, its ability to flower only once each year and with its peculiar annual radial increments of growth in the wood. Here is a bizarre object indeed! Organizational understand- ing of woody plants must come to terms with growth princi- pies in parts of the globe where they are most readily com- prehended, that is in the tropics. 1t is our intention to Preface XI make the future investigators' task an easier one by pre- senting a rational basis for future research. Acknoll'Iedgments. Organizations which have assisted in the preparation of this book include the Maria Moors Ca- bot Foundation and Atkins Fund, both of Harvard Univer- sity, which have pravided direct financial assistance. Dr. OLDEMAN was able to visit Harvard Forest in October. 1973 as a Éullard Fellow of Harvard University and was granted leave from the Office de la Recherche Scientifique et Tech- nique Outre-Mer to take up this appointment. We are indebted to Dr. MARTIN H. ZIMMERMANN, Director of the Harvard Forest, for facilities made available during this and other visits. Numerous other individuals have played important raies. Dr. HENRY S. HORN, Princeton University and Dr. JAMES WHITE, University College, Dublin (both at one time tempo- rary residents of Harvard Forest) read a preliminary draft of the manuscript and made numerous constructive and enjoyably pungent comments. They may still be dissatisfied with the final product, but this is simply because it reflects our prejudices and inadequacies. Several people have pro- vided us with useful information about tree architecture, including J.M. VEILLON, MARIE FRANÇ'OlSE PRÉVOST and G. CREMERS. Photographic and technical assistance in Peter- sham was provided by ANNE FAULKNER, MONIKA MATT- MÜLLER, USHER POSLUSZNY and REGULA ZIMMERMANN. Typing and editing of manuscripts has been the respon- sibility of SANDY WEIDLICH and DOTTY SMITH. In general the willing support of our differing institutions has been of great benefit during a task made difficult by our wide geographical separation and the continuing need to carry out our normal duties. We are thankful that our publishers have been patiently appreciative of this circum- stance. January, 1978 FRANCIS HALLÉ ROELOF A.A. OLDEMA:'-i PHILIP B. TOMLINSON Nore: Since frequent reference is made to HALLÉ and OLDEMAN (1970), for conciseness this is referred to as ""H.O., 1970'" in the text. Contents Clwf!tcr 1 Introduction A. What is a Tree') .. 1. Definitions .. JI. Tree Making 2 III. Apical Meristems and Tree Construction 4 I. Trees Built by One Meristem. 4 2. Trees with Modular Construction. 4 3. Trees with Trunk-Branch Differentiation 5 4. Trees with Changes in Orientation of Axes 5 B. The Botanical World of the Tropics 6 I. Distribution and Size of Flowering Plant Families 6 II. Tropical Floras as Tree Floras 8 III. Floristic Richness in Limited Areas. 10 IV. Geographie Locations. 10 V. Climate and Tree Growth in the Tropics 10 ("Iw/itcr;; Elcmcnts of Trcc Architecturc A. The 1 nitiation of the Tree 13 1. Seedling Morphology 13 II. .Iuvenility and Phases of Development 16 B. Apical Meristems and Buds 18 I. Terminal Buds 18 II. Bud Composition. 22 III. Lateral Buds 22 IV. Secondary Bud Complexes. n c. Extension Growth in Tropical Trees 24 I. Introductory Remarks 24 II. Rhythmic Growth 25 1. Rhythmic Growth in Hevea 25 2. Preformation and Neoformation 32 3. Further Examples of Rhythmic Growth 32 III. Continuous Growth 36 1. Palms 37 2. A Dicotyledon 38 D. Phyllotaxis and Shoot Symmctry 39 J. Primary Orientation. 39 II. Secondary Orientation. 39 XIV Contents E. Branching: Dynamics 40 1. Branch Order Terminology 40 II. Syllepsis and Prolepsis. 42 1. Definitions and Descriptions. 42 2. H istorical U sage of the Terms 44 3. Apical Dominance 45 Ill. Continuous and Diffuse (Intermittent) Branching 47 F. Branch Polymorphism: Long Shoots. 48 1. Orthotropy and Plagiotropy 48 1. Strict Orthotropy of Trunk Axes 50 2. Orthotropic Branches. 50 3. Plagiotropic Branches (Reversible) 52 4. Plagiotropic Branches (Nonreversible) 54 5. Phyllomorphic Branches. 55 II. Branch Complexes and Sympodial Growth 55 III. Plagiotropy and Syllepsis 57 IV. Plagiotropy in Monocotyledons. 58 G. Branch Po1ymorphism: Short Shoots. 59 1. 1n Dicotyledons 59 II. In Monocotyledons 60 H. A bscission 61 1. 1 nOorescence 61 1. Flowering and Shoot Construction 61 II. Continuous Flowering. 63 Ill. CauliOory 63 IV. Floral Phenology 64 J. Radial Growth: Conifers and Dicotyledons 64 1. Growth Rings 65 Il. Growth Rings in Tropical Trees 66 III. Cambial Activity in Tropical Trees 67 K. Radial Growth: Sorne Variations 68 1. Trees Without Secondary Growth. 68 1. The Palm-Habit 68 2. Bamboos 70 3. Tree Ferns. 70 II. Arborescent Monocotyledons with Secondary Growth 70 III. Cycads. 71 L. Root Systems in Tropical Trees 71 Chapter 3 Illhcrifed Trec Architecture A. The Concept of Architecture and Architectural Tree Models 74 1. The Architectural Continuum 74 II. Recognition and Study of the Architectural Models 77 Contents xv 79 259 .... 259 II 1. N omenda t ure IV. Recapitulation of Growth Criteria Used in Recog- nizing Models 80 V. Size and Architectural Proportions - Corner's Rules 81 B. Illustrated Key to the Architectural Models of Tropical Trces .. .... 84 C. Descriptions of Architectural Tree Models .. 98 1. Illustrations of the Models-a Note of Explanation 98 II. Monoaxial and Polyaxial Trees. 99 Ill. Plan of the Descriptive Arrangement 101 IV. Monoaxial Trees ]01 HOLTTUM'S Model 101 CORNER'S Model 109 V. Polyaxial Trees. 118 1. Vegetative Axes ail Equivalent and Orthotropic. 118 TOMLINSON'S Model 118 SCHOUTE'S Model 128 CHAMBERLAIN'S Model 133 MCCLURE'S Model 139 2. Vegetative Axes Differentiated into Trunk and Branch 145 LEEuWENBERG'S Model 145 KORIBA'S Model .... ] 55 PRÉVOST'S Model. 161 FAGERLIND'S Model ]67 PETrr's Model 1 n NOZERAN'S Model 177 AUBRÉVILLE'S M odel 182 MAssART's Madel 191 Roux's Model 200 COOK'S Model 206 SC ARRONE'S Model 213 STONE'S Model 217 RAUH'S Model. 221 ATTIMs' Model 228 3. Trees with Mixed Axes - an Introduction 232 MANGENOT'S Model 233 CHAMPAGNAT'S Model 238 TRoLL's Model 242 D. Architecture of Lianes 251 1. Lianes with an Architecture Conforming Closely to That of Tree Models . 252 II. Lianes with an Architecture Not Conforming to That of Known Tree Models 255 E. Architecture of Herbs: Miniaturization III Relation to Tree Models 1. Miniaturization of Models ... XVI Contents 2. Origin of New Models F. Architecture of Fossil Trees .. 263 263 C/wpter 4 0ppOrlllni.llic Trec Architecture A. Reiteration. .. 269 1. Reiteration as a Morphological Phenomenon 269 [1. The Organ Complexes Built by Reiteration. 275 1. The Tree in the Forest 275 2. The Free-Standing Tree 280 B. Energetics 284 1. Trees in Their Environment 284 1. Energy Exchange. 284 2. Energetic Efficiency. 286 3. Energetic Economy in Who le Architecture. 290 4. Spatial Disposition of Surface in Tree Crowns 292 5. Height-Diameter Re1ationship in Trees .. 294 6. Flexibility and Rigidity in Volume-Surface Integration ... 297 [1. Energy Exchange and Production. 302 1 [1. Size and Architectural Proportions 309 [V. Vigor and Death in Forest Trees 310 V. Ecological Strategies of Trees 315 C. Growth Potentiel! of Forest Trees 320 1. Trees of the Future 320 [1. Trees of the Present. 322 [[1. Trees of the Past 325 [V. The Morphological [nvcrsion Point 325 V. Gymnosperms and Forests 327 D. A Note on Floristics. 330 Chapter 5 Forest.l· and Vegetation 346 332 333 335 336 340 341 341 Theil' .. 342 346 II. The Architecture of Homeostatic Forest Plots 1. The Set of the Present. 2. The Set of the Future. 3. The Set of the Past 4. The [nfrastructural Set: Meristems 5. Geometry of Homeostatic Forests with Vertical Gradients .. Examples of Forest Plots 1. A Forest at Montagne La Fumée, Saül, French Guiana 1 [1. A. The Architecture of Forest Plots. 1. The Layered Forest. Contents XVII 2. A Forest at Trois Sauts, Oyapock River. French Guiana 352 3. A Forest at Tom Swamp, Harvard Forest, Massa- chusetts. .. ..... 354 IV. Morphological and Ecological Inversion Surfaces 356 V. Variations in Homeostatic Architecture 360 1. Forest Imbrication on Siopes. 360 2. Intcrtwining of Structural Ensembles 364 3. The Rivcrside Effect in Whole Canopies 365 4. Architecture of Forests with Strangling Figs 365 B. Sylvigenesis. .. 366 1. Disturbances of Existing, Functioning Forests 366 II. The Chablis 368 III. Homeostasis in the Forest. 370 IV. Sylvigenetic Cycles and Phases 375 V. Tree Ecotopes 380 VI. Biological Nomads and Towering Trees 383 Conc/liding Rcmarks 386 Glossorl'. 387 Refercnccs .... 392 lllde.v of Piani NO/17es and Theil' Modcls 413 SlIhjcet l//(In 429 Chapter 1 Introduction A. What is a Tree? I. Defïnitions The reader may find the concept of a "tree" used in this book a very generous one. On retlection we see that a tree is not easily defined or at least is definable in many different ways. Trees, in fact, are no longer the property of botanists, since to a mathematician a .. tree" is a system in which any two points arc connected via only one possible pathway (i.e., the system is not a reticulum and lacks loops). In this very general sense one may find trees in many disciplines - in heraldry as a genealogical chart (a family tree), in geomorphology as the tributaries of a stream system, in cybernetics as a deci- sion-making process. each providing an example of a mathematical trec. The di- chotomous kcy on page 84 is an example of such a tree. The mathematical concept of tree may have useful analytical and predictive purposes (OOHATA and SHIDEI, 1971; McMAHON and KRONAUER, 1976) and is helpful in constructing computer programs by which botanical trees may be mimicked (RASHEV5KI, 1944; LEGAY, 1971; FRANQCIN, 1970; LINDENMA YER, 1971). However, our concern is with botanical trees, which are still susceptible to a va ri- et y of definitions. Usually these involve size (a tree is not a shrub, nor a he rh) as weil as physiognomy (existence of a major axis or trunk). The most rigid defi- nitions are provided by foresters (e.g .. LITTLE, 1953. p. 5) - trees are .. woody plants having one crect perennial stem or trunk at least three inches (7.5 cm) in diamete rat breast height (4 1/ 4 ft) (1.5 m). a more or less definitely formed cro\vn of foliage, and a height of at least 12 ft (4 m)". This is a pragmatic definition used by a professional group for whom a tree is considered mainly as the source of merchandisable timber. By this defini- tion a tree only has one trunk, but we will see that this is not necessarily a con- stant feature. An ecologist is likely ta de- fine a tree, in terms of a plant's competi- tive ability, as a unit capable of casting shade on other plants. An anatomical definition would be conccrned with the rigidity of the plant, i.e .. its ability ta pro- duce lignin, and might even be restricted to plants whose trunks arc mainly madc up ofsecondary tissue. produced hy a \as- cular camhi.m (" wood" in a gcneral anatomical en se). Thus a palm might he excluded because its trunk is primary: a hanana is a "giant he rh ": bath. however. fit the forester's definition of a tree given ab ove, as does Afpillia hoia, a giant ginger whose aerial shoots arise l'rom an under- ground rhizome. Lianes are usually ex- cluded because they are not self-support- ing, but sorne woody epiphytes do con- l'afIn because they can reach the required proportions, even if by unconventional ways. From this it is clear that our concept of a tree is angiosperm-centered (with the conifers thrown in for good measure). i.e .. hased on the method of construction of a tree exemplified by an oak. a ruhher tree, or a pine. Howevcr. if we add a di- 2 mension of geological time we can appre- ciate that this concept is too limited, since the fossil record demonstrates many other, initially successfuL attempts attree- making, e.g., Lcpù/o!lclI!lroll, calamites, seed-ferns, in which branching patterns and anatomical principles are sometimes different l'rom those in angiosperms (see p. 263). Although largely extinct, a few of these "ancient ways" still persist as in the cycads or, on a lesser scale, in horse- tails (EquiscfWJI). The tree-ferns and most woody monocotyledons (e.g., palms) rep- resent examples of trees based on pri- mary, not secondary, construction and it is likely that these monocotyledons are a relatively recent experiment in tree-mak- mg. From this brief consideration of tree diversity it is evidently unwise to offer rigid definitions \vhere they are not needed. Consequently in this book our concept of a tree is implied in the plants discussed, ranging l'rom the oil palm, Cycas, Cyatl1c{[, the paw-paw, banana, dragon tree, ta commercial crops of the tropics like coffee, cocoa and rubber and to forest giants like Koolllpass;a, kapok, and sand box tree. We do not forget, how- ever, the slender treelets of the forest un- dergrowth, especially as they tell us so much about the diversity of growth ex- pression in woody plants. Even woody epiphytes, which may never develop a rec- ognizable trunk, have ta be considered. II. Tree M ak illg If we broaden our concept of a botanicaJ tree in this way so that it encompasses the diversity of large plants in tropical ecosystems it is of interest to consider the different ways in which plants become trees. The elements of a tree (Fig. 1) are crown, trunk or bole, and roots. The !ast, incidentally. never enter into the dcfini- Chapter 1 Introduction tion of a tree, although they are implicit in its growth. In the generally considered case crown. trunk, and root system are synchronous in thcir development, maintaining a con- stant proportion in parts. This method of construction is represented diagram- matically in Figure 1A and is, of course, the basis for the pipe model theory of tree form (SHINOZAKI et al., 1964). The developmental basis for this construc- tional method is the ability of the trunk to increase in diameter as it grows in height. In an alternative situation the crown may be developed first, at soillevel, and with it much of the root system. Sub- seq uently the crown is erected by exten- sion of the trunk, which maintains a con- stant diameter (Fig. 1 B). This is the method of tree construction based on primary growth which characterizes the palms and tree ferns. A variant of this is seen in the proliferation of trunks and crowns by basal branching, which has the advantage of making initial use of an ex- isting root system (Fig. 1 Cl. Multiple- stemmed palms, like the date, exemplify this and provide, incidentally, an example of a many-trunked tree. Both thcse major categories are charac- terized by a relatively slow development of the crown. In a third category. trunk and a large part of the crown are essen- Fig. 1 AD. Four ways of making a tree. [> A Crown. trunk and root system develop synchronously. B The crown and much of the roots develop first, at ground level, trunk extension comes later. C Proliferation of trunks and crowns by sub- terranean branching. D Germination on another tree, the .. trunk" is largely formed downward by roots (" strangler"). A and C l'rom left to right, Band D l'rom right to lelt; l'i'r/ical li/1('.\ in A and B symbolize the vertical pipe systems (SIIINO/Af.:' ct al., 1964)