Root Identification Manual of Trees and Shrubs: A guide to the anatomy of roots of trees and shrubs hardy in Britain and Northern Europe PDF
Preview Root Identification Manual of Trees and Shrubs: A guide to the anatomy of roots of trees and shrubs hardy in Britain and Northern Europe
ROOT IDENTIFICATION MANUAL OF TREES AND SHRUBS ROOT IDENTIFICATION MANUAL OF TREES AND SHRUBS A guide to the anatomy of roots of trees and shrubs hardy in Britain and Northern Europe D. F. CUTLER, P. J. RUDALL, P. E. GASSON AND R. M. O. GALE Jodrell Laboratory, Royal Botanic Gardens, Kew London CHAPMAN AND HALL First published in 1987 by Chapman and Hall Ltd 11 New Fetter Lane, London EC4P 4EE © 1987 The Trustees of the Royal Botanic Gardens, Kew Softcover reprint oft he hardcover 1st edition 1987 ISBN-13: 978-94-0lO-7912-9 All rights reserved. No part of this book may be reprinted, or reproduced or utilized in any form or by any electronic, mechanical or other means, now known or hereafter invented, including photocopying and recording, or in any information storage and retrieval system, without permission in writing from the publisher. BRITISH LIBRARY CATALOGUING IN PUBLICATION DATA Root identification manual of trees and shrubs: a guide to the anatomy of roots of trees and shrubs hardy in Britain and Northern Europe. 1. Roots (Botany) 1. Cutler, D.F. 581.1 '0428 QK644 ISBN·13: 978·94·010·7912·9 e·ISBN·13: 978·94·009·3141·1 DOl: 10.1007/978·94·009·3141·1 Contents Foreword by Professor Keith Jones page vii Preface ix INTRODUCTION 1 BIBLIOGRAPHY 6 GENUS DESCRIPTIONS OF DICOTYLEDONS 7 FAMILY DESCRIPTIONS OF GYMNOSPERMS 211 APPENDIX 231 Table 1 Diagnostic characters in root anatomy of Dicotyledon trees 233 Table 2 Diagnostic characters in root anatomy of Dicotyledon shrubs and climbers 234 Table 3 Main differences in root wood anatomy in four related genera: Alnus, Betula, Carpinus and Corylus 236 Table 4 Diagnostic characters in root anatomy of the family Caprifoliaceae 236 Table 5 Diagnostic characters in root anatomy of Gymnosperm trees 237 Index of scientific names 239 Index of common names 244 Foreword Plant anatomy is a vital part of plant descriptions and an integral component of taxonomy. It also provides a unique means of botanical identification of plant fragments and artefacts. The science in all of these roles has prospered for many years at the Jodrell Laboratory which is renowned as a principal world centre for the subject. Its reputation resides to a large extent in the substantial series of reference works on the systematic anatomy of dicotyledons and monocotyledons written by staff of the Anatomy Section in collaboration with researchers in other institutions. This present book, however, is the first from Kew to describe a single organ - the root - to provide a means of identification of a range of trees and shrubs when only the root is available. It has been inspired by the many root samples sent to the Jodrell Laboratory over the years, often when they seem to have been concerned with damage to the foundations of buildings. A previous book Tree Roots and Buildings written from the Anatomy Section by Dr D. Cutler and I. Richardson addressed itself to the frequency of damage of this sort caused by a range of tree species. In the present book the Jo drell anatomists now expose the secrets of their diagnoses making it possible for others to recognize the plants from which roots are derived. It is a detailed and comprehensive work written by colleagues, all of whom are dedicated and highly authoritative scientists. It gives me particular pleasure not only as a demonstration of one of the important practical applications of anatomy, but also of concern for human welfare which is the hallmark of the research carried out in all of the scientific sections of the Jodrell Laboratory. KEITH JONES Keeper of the Jodrell Laboratory and Deputy Director Royal Botanic Gardens Kew vii Preface This book is the result of teamwork, not only among the authors, but also many other people, most of whom are or were on the staff at Kew. Over a period of about twelve years a lot of energy went into building up a large collec tion of reference microscope slides of shrub and tree roots. This enabled accurate identifi cations to be made of short lengths of root. Most of these came from inspection holes at the foundations of buildings when it was suspected that roots might be related to damage. The unique working collection has formed the basis for this book, but we have added to it to extend the range of species covered and increase its value. Although the majority of the working slides proved suitable for photography, some were not. Most of these were replaced with new slides, but when no additional material was available, some had to be photographed despite their quality. Roots of different diameters were studied for many of the species examined. The descriptions include information on any variation that occurred in these, but the most representative were selected for the illus trations. Among those helping with sectioning were Timothy Lawrence and former staff members Frederick R. Richardson and Dorothy Catling. Ian B. K. Richardson, co-author of Tree Roots and Buildings also assisted. Charles Erskine and his staff in the Living Collections Division have gone out of their way to help dig up roots for us. The Photographic Section, with Tudor Harwood, Milan Svanderlik and Andrew McRobb have worked under pressure to print the large number of photographs. Nigel Taylor assisted with verification of plant names, and Mary Gregory made a critical reading of the text. Valerie Horwill typed the manuscript. We are most grateful to all who have helped us. ix Introduction Knowledge about root structure has implications far beyond the intrinsic academic interests of plant anatomy, physiology and ecology. It has become necessary to be able to identify trees and shrubs from their root structure for reasons of considerable economic importance, and for preservation of the amenity value of the plants concerned. Roots of trees and shrubs have frequently been implicated in damage to buildings through their effects on foundations and blockage of drains. Two recent drought periods have emphasized the problems. When it is suspected that roots are involved in damage of one form or another, it is most important that there should not be indiscriminate removal of trees and shrubs. Equally, from the legal point of view, it is important that the owner of the trees or shrubs involved should be identified. In most instances it is possible to remove roots from the site of damage, and by an examination of their internal structure, identify the plant from which they have come. Root wood structure often differs from twig or branch wood structure in the same plant. Consequently the reference books on the secondary wood of the aerial parts have been of only limited help in making identifications. Over a period of about twelve years, staff in the Plant Anatomy Section of the Jodrell Laboratory at Kew have been making microscope slides of root sections from authenti cated sources. These have been used as reference material to assist in the identification of roots thought to have been involved in damage to buildings or drains. This work, and a survey of root spread that was undertaken simultaneously, led to the production of the guide Tree Roots and Buildings by D. F. Cutler and I. B. K. Richardson. It was decided to put the unique reference collection of microscope slides of roots to further use, and make some of the information it contains more widely available. The opportunity was taken to extend the collection to cover most of the trees and shrubs that are known to be hardy out of doors in the British Isles. Consequently, many' exotics' were studied, in addition to native plants. These photographs have been brought together in this volume. Because of the very large number of microscope slides available often representing several specimens with a range of diameters, and range of variability in some species, it proved a difficult task to be selective, and yet give a comprehensive cover in a book of manageable proportions. Illus trations included here show the salient points that are of diagnostic value. In most examples a transverse section (TS), radial longitudinal section (RLS) and tangential longitudinal section (TLS) are provided, together with a brief description of the more important features, and notes on their diagnostic value. Both wood and bark are described. In certain families of plants, the genera cannot be distinguished from one another on the basis of root anatomy alone. In such instances the description of a group of 1 INTRODUCTION genera may extend beyond the normal two page layout, with illustrations taken from a number of genera or species. Examples may be found in the Rosaceae, where the sub family Pomoideae is described rather than genera, and in the Salicaceae where Salix and Populus are described together. The alphabetical arrangement by scientific name has been chosen for convenience, rather than one based on systematics. The gymnosperms (including Ginkgo) have been placed in a section separate from the flowering trees and shrubs, and are described within their families. There are relatively few diagnostic characters in transverse sections of gymnosperm woods - those without resin canals tend to look very similar to one another. Consequently, for the gymnosperms space has been given to the longitudinal planes of section in preference to transverse sections. It is envisaged that most users will have some background in plant anatomy, but for those who have not, or wish to brush up earlier knowledge, this introduction gives basic details useful in interpreting the descriptions. All the roots illustrated in this book show secondary growth in thickness. Some are juvenile and have very few growth rings. All have expanded to the extent that their original epidermis (rhizodermis) has split and in many specimens, gone. Bark The 'bark' of the root, as defined for this book, consists of the cork (phellem), phellogen and phelloderm, any remaining layers of cortex, and the phloem. Cork is produced by a cork cambium (phellogen). This may be formed in the cortex, at varying depths, or in the outer phloem, or rarely, from the rhizodermis itself. The cork provides protection against the ingress of pathogens. In some species cork provides few features of diagnostic value. In others there are characteristic layers of cells with thick or thin walls. There is variation in the way the cork layers split and are shed. The cells may lack contents, or contain dark coloured substances frequently identified as tannins. If the cortex is to the outside of the cork, it eventually splits and is shed; fragments may persist in young roots. When cortical cells persist to the inner side of the cork, they remain alive, and frequently become involved in cell division, so accommodating growth in root diameter without tearing. A clear dilatation (expansion) zone may be present, or the junction between cortex and the dilating ends of phloem rays may be indistinct. Since no developmental studies were carried out during the preparation of this book, we have decided to make no distinction between dilating ray ends and divided cortical cells in descriptions. The cortex may consist entirely of parenchymatous cells, or it may contain sclereids and fibres, or both. Some cells may be tannin-filled, crystals of various sorts may be present and sometimes diagnostic features such as mucilage cells or secretory ducts may occur. Phloem is sufficiently variable for diagnostic characters to be identified in transverse sections. Normally two distinct tissues are evident, the rays and the conducting cells. Rays may remain the same width through the phloem, or they may expand or dilate to varying extents towards their outer ends. Dilatation may be due to cell expansion, cell division or both. The conducting tissues may all be thin-walled, consisting of sieve-tubes, companion cells and parenchyma (or sieve cells, albuminous cells and parenchyma in 2 INTRODUCTION gymnosperms). However, in many species sclereids and fibres are also present. These thick-walled cells may be scattered at random, arranged in strands or groups, or in tangential bands, alternating with thin-walled cells. Cambial zone The cambial zone consists of the vascular cambium itself, and the immediate undifferen tiated phloem and xylem cells to either side. After the first year of secondary growth, the cambium generally assumes a cylindrical or compressed cylindrical form. In some species, the cambium may curve distinctly towards the root centre at each of the wide rays. Xylem The primary xylem, with its archs of protoxylem is often distinct at the centre of second arily thickened roots. There is generally no central pith. The number of protoxylem archs is often related to the initial width of the primary root, and has little if any diagnostic value in the dicotyledons. Many gymnosperms are diarch. Nearly all the characters of diagnostic value come from secondary xylem. Transverse sections show some features clearly, and longitudinal sections show details of others. In narrow roots it can be difficult to make accurate tangential longitudinal sections, quite frequently there are features of both radial and tangential cell arrangement in such sec tions. In transverse section, growth rings mayor may not be distinct. Some species regularly have ring or semi-ring porous vessel distribution, whereas others are diffuse porous. Dendritic and other distinctive types of vessel arrangement are noted when they are present. All of these characters appear to be more variable in roots than in stems. Some species have only solitary vessels, but it is more common to have both solitary and grouped vessels. Characteristic vessel groupings are noted in the descriptions. Vessel diameter is very variable in roots, and even in the same species examples may be found with narrow vessels and others with much wider vessels. The growing conditions have a marked effect on vessel width. In this book we have described vessel width when appro priate, but the dimensions that relate to our samples may represent only part of the possible range for a species. Because of this, no actual measurements are given in descrip tions, and details of equivalents of width and cell wall thickness are given in the following section which acts as a general guide. In the longitudinal sections (LS), details of vessel to vessel (intervascular) wall pitting, and vessel to ray pitting are noted. This is of high diagnostic value. In the gymnosperms, tracheid wall pitting and cross-field (tracheid to ray) pitting have similar significance. Vessel perforation plate types are also described; these are generally easy to see, and are very valuable in diagnosis. Tyloses are described when present. Sometimes vessels or tracheids (and fibres) may have a tertiary spiral (helical) thicken ing of the wall next to the lumen. Fibres in roots frequently have thinner walls than those in stems. Mention is made in descriptions of wall thickness and lumen width when appropriate. Often root samples are too narrow or otherwise inadequate for detailed studies to be made of the complete 3 INTRODUCTION range between fibres and tracheids and their intermediate forms. In diagnosis this could be of importance, but because of the practical difficulties we have noted only when fibres have conspicuously bordered pits (technically making them fibre-tracheids) rather than non-bordered or only very slightly bordered pits. For the same reasons, only imperforate tracheary cells with very distinct bordered pits have been recognized as tracheids in this work. The distribution and abundance of axial parenchyma is recorded for transverse sections. It is often more abundant in roots than stems of a given species. In LS, note is made of important features of the axial parenchyma, for example, if it is storied, or if cells are mainly fusiform. Rays are described in both TS and LS, since both views are essential before the ray type can be discerned. Ray width can only be established accurately from the TLS. Details are given about the shape of rays, whether they are homocellular with all cells similar in shape, or heterocellular, composed of cells with distinctly different shapes. Many narrow roots have not developed the mature ray types. It is not wise to use the established ray classifications for this reason. Height of rays is of importance, and is recorded. The presence and type of crystals, cell contents (particularly starch granules), secretory canals or ducts are recorded as appropriate. In this book the text, captions and illustrations must be used together to gain infor mation useful for identification. The textual descriptions by themselves are not complete, but emphasize details of value for diagnosis. Tables are provided in the appendix to assist in the process of identification. The best book can act only as a guide to the possible identity of roots. Comparison of the unknown with accurately identified reference microscope slides is normally necessary before the process of identification can be completed. Measurements There is a great deal of variation in cell width and wall thickness in roots of a given species, much more so than in twigs or mature stem wood. Consequently accurate measurements are not generally very useful in identification of roots. Often the root sample is inadequate for statistically accurate measurements to be made. It was decided not to give actual figures in the descriptions for these reasons. A general guide may be of interest to some readers, so the descriptive terms used are defined here. Fibre wall thickness and lumen width is given in general terms. In fibres with narrow lumina, the double wall thickness (of adjacent fibres) is greater than the width of the lumen. In fibres with wide lumina, the double wall thickness is narrower than the lumen. Fibres described as thin-walled, have single walls narrower than 2 J.tm. Vessels are described as wide when the tangential lumen diameter is greater than 100 J.tm, and narrow when less than 50 J.tm. The size of intervascular pits may be of diagnostic value, and tends to be less variable within a species than many other measurements in roots. Those described as coarse are over 6.5 J.tm in diameter, and fine pits are 4 J.tm or less. Where pit size is unspecified, the pits are between 4 and 6.5 J.tm in diameter. In Betula, the pits are minute, generally less than 3.5J.tm. 4
The list of books you might like
