Broadleaves

Text by the late Herbert L Edlin

Revised by Alan F. Mitchell forestry Commission

Her Majesty Stationery Office Hmso

LONDON: HER MAJESTY'S STATIONERY OFFICE

© Crown copyright 1985 First published 1963 Reprinted with amendments 1975 Second edition 19S5

HER MAJESTY'S STATIONERY OFFICE

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Government publications are also available [trough booksellers

Acknowledgements

Line drawings by Christine Darter, except Figure 58 which is by John Williams.

Colour photographs from the Forestry Commission collection, or by Maurice Nimmo where indicated.

Enquiries relating to this publication should be addressed to the Publications Officer. Forestry Commission Research Station, Alice Hoit Lodge. Wrecdesham, Farnham, Surrey GCJ10 4LH

Contents

4 INTRODUCTION

MAPLES AND SYCAMORE 8 Acer campestre

10 Acer platanoides

11 Acer pseudoplatanus

HORSE CHESTNUT 14 Aesculus hippocastanum

ALDER 16 Alnus glutinosa

STRAWBERRY TREE

18 Arbutus unedo

BIRCHES

19 Be tula péndula 21 Betula pubescens

24 Buxus sempervirens

HORNBEAM 26 Carpinus betulus

SWEET CHESTNUT 28 Castanea sativa

HAZEL 30 Corylus avellana

BEECH 33 Fagus sylvatica

ASH

36

Fraxinus excelsior

HOLLY

38

Ilex aquifolium

WALNUT

40

fuglans regia

PLANE

42

Platanus X acerifolia

POPLARS

45

Populus alba

48

Populus canescens

50

Populus nigra var. betulifoba

52

Populus nigra 'Italica'

53

Populus 'Regenerate'

54

Populus 'Serótina'

56

Populus trémula

59

Populus trichocarpa

WILD CHERRY

60

Prunus avium

OAKS

63

Quercuscerris

65

Quercusilex

67

Quercus petraea

70

Quercus robur

73

Quercus rubra

ROBINIA

75

Robinia pseudoacacia

WILLOWS 78 Sai,* alba SO Salix alba 'Coerulea' 82 Salix caprea 85 Salix fragilis

ROWAN 87 Sorbus aucupaiia

LIME

91 Tilia X europaea

ELMS 94 Ulmus glabra

96 Ulmus x boüandica 'Vegeta'

97 Ulmus procera

100 Ulmus cupinifolia vac. comubiensis 103 INDEX

SFEQMEN TREES IN COLOUR Between pages 64 and 65

Introduction

Thebroadleaves, or hardwood trees, are the leading feature in the British landscape of woods and hedgerows. In the past they were the country's main source of building material, fencing, and fuel. Today, when we have other sources of heat and power, and steel and concrete play so large a part in building, the hardwood timbers of these attractive trees are less important to our economy, But there is still a very substantial trade in good sound oak, beech, ash. sycamore and lime, for the better classes of furniture making and joinery, while poplar is used for crates and boxes, and willow for cricket bats.

To a growing extent, the country's needs of timber in bulk are nowadays met by the conifers, or softwood trees. The main timber-yielding kinds are described in detail in the companion volume Conifers (Forestry Commission Booklet 15. HMSO).

Most forest planting today is done, inevitably, with these conifers. But the landscape, shade and shelter values of the broadleaves are so great that they are always likely to play the larger part in hedgerows, as street trees, and in general amenity planting. Some of them are natives, and these are firmly established in old natural, or semi-natural, woodlands throughout the British isles.

Our broadleaved trees form part of the vast natural broadleaved forest of northern Europe, which once stretched, almost unbroken, from the Atlantic to the steppes of Russia, Similar forests are found in eastern Asia, on the upper slopes of the Himalayas, and right across North America. The key feature of all these woods and trees is. as the name implies, the broad leaf, which is shed each autumn as the colder weather approaches.

The leaf and its work

Only a few of our broadleaves, such as box, holly and evergreen oak, retain their leaves through the winter months. All the rest lose them in the autumn, and pass through the coldest part of the winter with branches and twigs bare, and with their delicate shoot tips hidden within resting buds. This enables them to survive through the unfavourable period for growth, when the shoots might well be damaged by frost, by winter storms battering the leaves to fragments, or by drying out when the soil is frozen or too cold to yield its moisture. The few broadleaves which keep their leaves in winter also have protective buds, and their leaves are tough and waxy like many of the evergreen conifers to resist water loss.

The alternating leafy and leafless phases in the life of the deciduous tree reflect the changing seasons. In spring, as the land warms up, a new set of leaves expands from opening buds, clothing the branches with fresh, bright green foliage. All summer through these leaves carry out their essential function of absorbing and using the energy of sunlight to manufacture organic food materials by the remarkable process of photosynthesis. Every leaf contains within it the substance chlorophyll, which gives it its green colour. In sunlight, and in the presence of sufficient moisture, the chlorophyll uses the light energy to make chemical substances which can later release energy for growth, or else be used to build up the tree. Carbon dioxide, present in the air within and around the leaf, is combined with water to form energy-rich sugars. Together with mineral salts absorbed by the roots, these are transformed by intricate chemical processes into all the complex materials that make up the tree's substance - wood, roots, flowers and seeds, as well as the leaves themselves.

In autumn, the tree withdraws much of the mobile food material from its leaves, which slowly change colour from green to brown, yellow and red, or orange. Then, their work done, they fall away from a definite point of union with the twigs, leaving behind them small leaf scars. Already the tree has made preparations for a fresh crop of leaves in the ensuing spring, and the buds from which these will spring can be seen already formed, waiting for their long winter rest.

The falling leaves, drifting to the forest floor, decay to make a rich mould, still holding mineral nutrients. This leaf litter forms a fertile addition to the soil in which the trees' roots live and feed: in fact it returns to the ground the vital minerals won earlier.

A few of our broadleaved trees are evergreen, and their Leaves have a longer cycle of life. Some of them, like the holly, ate native; Others come from southern Europe, or from other countries with a 'Mediterranean' climate of warm moist winters. Each leaf on an evergreen broadleaf tree lasts for several years; every year new ones are added, and a few of the older ones fall, usually in the summer, but the tree as a whole is never leafless.

The timber of broadleaved trees is known as hardwood, because in most kinds, though noi all. it is physically much harder than that of the conifers, or softwood trees, its structure, as seen under the microscope, is very complex, and varies a great deal from one kind of tree to the next. This results in a fascinating variety of appearance and working properties, which makes certain timbers far more suitable for certain work than others. Ash, for example, makes tough axe handles, whereas elm is used for chair seats since it never splits.

How to know the broadleaves

All broadleaved trees belong to the great natural order of plants called the Dicotyledons, which are distinguished by having two seed-leaves or cotyledons in every seed. There are numerous families of these plants, many of which include both trees and smaller plants. Each family is defined, in a rather complicated way, on the basis of the structure of its flowers. This approach 10 naming trees, though essential for the botanist, does not help the ordinary enquirer very much. The flowers of trees are, in any event, apt to open high up in the crowns, they are only available for a few weeks each year, and - when you examine them - they often prove to be exceptional for the plant family concerned, or to be very much like those of some unrelated tree. Tree flowers are often grouped in catkins, and as a rule each catkin carries only male, or only female. Sowers, which gives the investigator further problems,

A more practical approach is to learn the characters of each genus of trees, with the aid of a book such as this, which brings out their key features. Each plant familyismadeupofoneormore genera, the members of which show a common pattern of bud, leaf, fkrwer, and fruit. Each genus, in tura consists of one or more species. distinguished by much smaller points of difference.

The names used for both genera and species are Latin or Greek ones, and the generic name, with a capital letter, always comes first Thus, Fagus sylvatica, the common beech tree, belongs to the species sylvatica, within the genus called Fagus. These scientific names are used by botanists and gardeners in all the countries of the world, although the trees also have local names in each local language. Thus, beech is Buche in German, and Hêtre in French, but it is Fagus sylvatica wherever it may be found.

The full quotation of a scientific name requires the addition of the name of the botanist or 'authority' who first published that name, along with a full description of an actual 'type' specimen. 'L' stands for Unnaeus, the famous Swedish botanist Carl von Linné who named many species. Authorities for scientific nomenclature are not included in this booklet but may be found in reference books which give more detailed descriptions of broadleaved trees.

As a handy working plan, the trees described in this booklet have been grouped alphabetically by their generic names, followed, again alphabetically, by the name of each species. The common English name of each tree is given as a sub-heading.

Once you know the characters of the genera of trees that are grown in Britain, it is fairly easy to get to know most of the trees that grow wild in temperate Europe. Asia and North America. All our common genera are found in those lands, so all you have to learn are the distinguishing features of the local species which may differ from those we know in Britain.

Whenever possible, work with two or more features from every tree that you wish to name. Single characters, such as buds, may be much alike, but a combination of bud. leaf and fruit is unique for any of our common trees,

Key characters of tree genera

To identify trees you must examine each of their features on a predetermined plan, knowing just what you are looking for. The illustrations in this booklet are designed to bring out key characters in a comparable way. Leaves, twigs and buds on both very young and very old branches may not be true to type; look therefore at specimens from average branches of a medium age.

General tree form and branch pattern

This may be seen in the colour illustrations of specimen trees. Each species exhibits a typical pattern of growth. Individual trees vary much with age, size, and situation, yet every sort of tree shows a character peculiar to its kind. This arises in large degree from the arrangement of the buds and twigs that eventually grow out into larger branches and trunks.

Bark

This is not illustrated here, except incidentally as part of a large tree photo, but notes on the more distinctive barks will be found in each text description. Bark varies a great deal, even on the same tree, with the age and size of the twig or branch concerned It is a great help to the experienced forester, accustomed to living with trees of all ages and sizes, but rather confusing for the beginner.

Twig and bud

Twigs and buds are of great value for identification because they are so easily found and are so constant in design for each sort of tree. In the winter months they are the mam clue to a tree's identity, and even in summer the bud pattern is easily revealed by stripping away expanded leaves. It is only hard to see during a few weeks in spring, when the leaves are expanding.

A key drawing of a typical winter twig is therefore included for every tree shown. Points to look for are:

  • a) Are the buds solitary and alternate, or are they grouped in opposite pairs?
  • b) Are they blunt or pointed?
  • c) Do they show, on their surface, many scales or only a few?
  • d) Are they large or small in relation to the twig that bears them? Below most buds comes a scar, left by a leaf that fell last autumn: the size and pattern of this scar often helps identification. So does the general character of the twigs, difficult to describe in words but well shown in the drawings.

Leaf

There is a wonderful variation in the structure of a leaf. The tough, dark green, leathery leaves of evergreens will at once mark them out When you examine the softer leaf of a deciduous tree you should ask these questions:

(a) Is it a simple, undivided leaf? Or one split into many lobes?

Or one divided into leaflets, that is, a compound leaf?

  • b) What is its general shape - long and slender, round and broad, or something in between?
  • c) Is its edge toothed or smooth?

Flower

The flowers of broadleaved trees are available only for a short spell in spring, and for most kinds it is necessary to examine both male and female ones to learn the full story. They have been shown in considerable detail in our drawings. Questions to ask when naming a tree that is in flower include these:

  • a) Are its flowers catkin-like, or do they bear large petals and sepals like most common flowering plants?
  • b) is the catkin examined a male one or a female one? Having picked out - possibly with the aid of a hand lens - the male stamens or the female pistils, you should compare them with the detailed pictures. Both the details and the general shape of the catkins help to identify each tree.

Fruit

Autumn fruits and seeds provide the most easily recognised features of every tree and for this reason they are also shown in detail in the text drawings. Technically, a fruit is the product of a single flower, and may consist of a single seed or else hold many seeds. But with many trees the feature that first strikes the eye is a fruit-duster, or fruit-catkin, built up of the fruits of many small flowers. It is often more helpful to observe the general character of this fruit-duster than to consider how each unit of it should be dassified botanically.

Points to look for on fruit-dusters, fruits and seeds, indude the following:

  • a) Are the fruits or seeds borne in groups or spaced singly and well apart?
  • b) Are the fruits succulent, or hard and dry?
  • c) Do the seeds bear wings, or tufts of hair, or not?
  • d) Are the seeds large hard nuts, or small fine grains?
  • e) What is the shape of the pod. husk, or cup that bears them? Remember, use more than one feature, if at all possible.

All the drawings in this booklet have been made from living material at a definite phase of growth. Nearly all of them are the work of Mrs. Christine Darter; a skilled botanical artist who has selected and verified the identity of all the plant material she has shown

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    Are broadleaves smoothed?
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