The Complete Guide to Compact Trees and Shrubs E-Book

Duncan Coombs

• Herausgeber: The Crowood Press
• Kategorie: Lebensstil
• Sprache: Englisch

Seitenzahl: 516

Veröffentlichungsjahr: 2023

Beschreibung

Featuring over 1,000 different trees and shrubs. A common problem that confronts today's gardener, garden designer or horticulturalist is a lack of growing space. But in recent years, plant breeders and nursery owners have recognised this and there is now an inspiring array of compact trees and shrubs to choose from for even the smallest of gardens. This book guides the reader through the considerable range of small trees and compact shrubs now available, with full details on their cultivation requirements and how to incorporate them into a wider garden design. Understand how trees and shrubs are produced and learn how to select with confidence at the plant nursery or garden centre. Consider how trees and shrubs may be best chosen and placed when designing a new garden, or replanting an established site. Browse the book's directories of over 100 separate genera and 1,000 individual plants, each with details of hardiness (using both RHS and USDA ratings); growing requirements; height, spread and habit; main features, including flowers, foliage and bark; and wider garden design considerations.

Leseprobe

CONTENTS

1 What Makes a Compact Tree or Shrub?

2 Trees and Shrubs in Garden Design

3 Directory of Suggested Trees

4 Directory of Suggested Shrubs

5 Directory of Suggested Conifers

6 Directory of Suggested Calluna, Daboecia and Erica

Appendix I: RHS Hardiness Ratings

Appendix II: USDA Plant Hardiness Zones Maps for the US and UK

Appendix III: Symbols and Abbreviations

Bibliography

General Index

Plant Index

Common Name Index

Acknowledgements

CHAPTER 1

WHAT MAKES A COMPACT TREE OR SHRUB?

The aim of this book is to produce a select list of trees and shrubs with all the necessary accompanying information to allow the would-be planter to choose with confidence ‘the best plant for the intended space’.

Malus × robusta ‘Red Sentinel’ provides bright-red crab apples right through the seasons from autumn to the following early spring.

A problem that confronts today’s garden designer is often a lack of space.

Worldwide there is a lack of space. Increasing population means less space for each individual. In the developed world, increasing demand for land for building on has led to an increase in the value of land. Increased value has, in turn, led to increase in building density and increase in the use of vertical space, as so ably demonstrated by cities such as New York, Tokyo and, to a lesser but increasing extent, in London with skyscraper buildings. Roof gardens, green roofs and green walls have begun to proliferate, and many of these incorporate carefully selected compact trees and shrubs. In less pressurised situations we see greater use of ‘brown field’ sites and the increasing development of three-story or more town houses.

The traditional view has been that trees and shrubs are always large and can’t be used in a small space, but many new cultivars are smaller, being specifically bred and selected to be more compact.

This book informs the reader of the large and often new range of compact trees and shrubs, which are so valuable when planting modern gardens, and how they may be used in modern garden design.

WHAT CONSTITUTES A COMPACT TREE OR SHRUB?

A modern approach would be to consider as a tree any plant that has a permanent branch structure, is large and perhaps dominant in a garden or planting. This idea is, however, dependent on context, since a plant such the slow-growing maple, Acer palmatum ‘Dissectum’, forms at maturity a mounded shape approximately 1.5m (5ft) tall and 2m (6ft 7in) across. In a small garden this would constitute a tree, but in a larger garden this would only be perceived as a shrub.

How a nurseryman (or nurserywoman) decides to produce and market a plant can alter its function in the garden. Fairly vigorous shrubs of normally flexuous, pendulous or creeping habit can be grown as a single stem that is trained upwards to a height, usually about 1.8m (6ft) and then the leader allowed to fall over in a natural way. This, coupled with later formative pruning, transforms a shrub into a small, compact tree. Using this technique, plants such as Cotoneaster ‘Hybridus Pendulus’, often used for low-growing ground-cover, can be converted into a compact, pendulous tree.

Acer palmatum ‘Dissectum’ in all its autumn glory. A plant such as this would be regarded as a shrub in a large garden, but as a tree in a small garden.

Cotoneaster ‘Hybridus Pendulus’ trained and then grown as a small tree.

THE KINDS OF TREES AND SHRUBS AVAILABLE

The Basic Material

As a result of the relatively recent last Ice Age and the slow recolonisation by plants, the UK has a rather small range of what are considered ‘native’ species. The paucity of the UK’s native plant species and, more recently, decreasing garden size, led initially to a demand for a greater range of suitable plants. Plant hunters, most significantly our Victorian forebears, travelled to far-off lands to search for, collect and introduce new plant species, many of these being trees and shrubs. The exploits of these often intrepid and brave collectors are well documented and we, as gardeners, owe much to them for the very wide range of plants we can grow in our gardens. Some of this plant collection did produce bad consequences with habitat damage and, indeed, the possibility of plant extinction in the wild, in some cases.

Today, the introduction of new plants from the wild is very heavily regulated with international treaties banning the import and export of wild plants, except for scientific research.

The trade of plants across the world has expanded greatly in recent years. Driven by the demand for more and more plants to green our environment and inside our home, this trade has flourished. This movement of plants across international boundaries has, however, caused some problems, in particular the spread of plant pests and diseases. Plant phytosanitary regulations have been set up, but such pests and diseases are no respecters of regulations! Unfortunately, there have been several serious incidences of such introductions, perhaps the most infamous being of so-called Dutch elm disease and, currently, the threat of Xylella.

This has led to a demand for the practice of local sourcing of plant material from within a country’s boundaries. In the UK, there is now a strong campaign for plant wholesalers, plant retailers and the plant-buying public to ‘Buy British’. Imported trees and shrubs for sale should now carry a plant passport attached to them to indicate that they have passed phytosanitary regulations.

PLANT BREEDERS AND SELECTORS

The demand for new cultivars, often of a smaller size to suit smaller gardens, has stimulated the activity of plant breeders and selectors. A few nurseries and their propagators stand out in this respect, having produced many new cultivars, in an almost bewildering range, some notably smaller and more compact. Nowhere has this been developed and pursued more than with the conifers. This group has proved to be genetically very adept at producing new forms, both during their production from seed and in sports arising spontaneously from growing plants.

Elsewhere in shrubs, nurserymen have been able to spot any useful variation in their stocks. Over many centuries specific plants and genera have received enormous attention. In Japan and China, Acer palmatum has been cultivated and selected to a point where hundreds of different cultivars exist, many very well suited to the small garden. In China, an activity largely unknown in the West, the selection of different forms of the evergreen shrub Osmanthus fragrans, has also been practised for over a millennium. This shrub produces the most beautifully scented flowers in winter and spring, and for this the plant is greatly prized.

In Europe, selection has also been focused on evergreen shrubs, with mutations causing leaf variegation being a source of many new plants. Variegation is usually due to a fault in chlorophyll production, the green pigment present in leaves. Variegation causes reduced vigour in the plants and new leaf colour forms. Such new plants, often being small and compact and in numerous different colours, are very appealing to modern gardeners. Unfortunately, the commercial pressure to release these new, desirable cultivars to the buying public has resulted in the release of some poor plants. Ideally, these plants should be trialled over time for their hardiness and propensity to revert to the original green plant.

THE PRODUCTION AND SALE OF TREES

Trees may be sold as seeds, seedlings, whips and feathered whips. Seedlings have been produced for forestry plantings for many years. More recently, young seedlings of ornamental trees and shrubs, some of which are difficult to germinate, have appeared on the market.

Seedlings may be sold for several purposes, including:

• Use as hedging plants.

• As young trees to be grown on into larger trees for subsequent sale.

• For use as understocks, on to which other cultivars may be grafted.

The way the tree seedlings are cultivated in their initial years may affect their suitability for certain uses and their price. The method of tree production, their height and whether or not they have feathers, are usually mentioned when they are offered for sale.

Young seedlings in their seedbed can have several different treatments. They can just be left to grow, which is acceptable for a year, possibly two. After this the young trees may become excessively drawn by growing too close together and begin to develop a tap root (a root that just descends downwards without branching). A root system consisting of just a tap root is undesirable since such plants have been found not to transplant well. Excessive drawing upwards results in a tree that cannot support itself – very undesirable.

To overcome these problems, the seedlings can be dug up, called lifting, and then transplanted. The process of lifting the young tree breaks the developing tap root. This is desirable because this encourages a fibrous root system, which subsequently will transplant well. Upon replanting, each seedling is given more space in which to grow, thus reducing the problem of the plants being drawn upwards.

A cheaper way of preventing the development of a tap root is to undercut the root system of the seedlings. In the tree nursery this is done by a tractor blade, which is drawn through the soil below the seedlings. This blade cuts the developing tap root, stimulating the development of the desirable fibrous root system. This undercutting, whilst cheaper than transplanting the seedlings, does not, however, solve the problem of tree overcrowding.

During the young tree’s growth, it may or may not develop side-shoots, called feathers. If the seedling is intended for use in forming hedging, then this is an advantage. Clearly, as the young trees grow, they become taller.

All these variables result in a grading system being employed to tell the potential purchaser how the tree has been produced, its suitability for various uses and it helps to justify different prices.

The Grading System for Seedlings and Very Young Trees

Trees are graded for height, usually in 10cm (4in) divisions.

They are graded for whether or not they are feathered. Feathered trees are better for hedging. Unfeathered trees, called whips, may be better for growing on to form larger trees or for use as understocks. Tree seedlings intended for use as understocks may also be graded for stem thickness.

An indication as to how the young plants have been produced is also usually given:

•1+1 indicates that the seedling has been grown in the seedbed for one year and then transplanted.

• 1+1 indicates that the seedling has been grown in the seedbed for one year, undercut and then grown on in the seedbed for another year.

As the trees are grown on, this may become more complicated, but still understandable, and will affect the value of the young trees offered for sale, e.g. 1+2+1 indicates that the seedling has been grown in the seedbed for one year, undercut, then grown on in the seedbed for a further two years, then transplanted and grown on for a further year.

This is a somewhat complicated system, reflecting the initial complexity of producing young trees, but a system that the purchaser is advised to study and understand, so that he/she can purchase young trees best suited for their purpose.

Trees in the UK beyond the young stages detailed above, may be grown to conform to British Standard BS 3936. This standard is produced in ten sections, of which BS 3936-1-1992 Nursery Stock: Specification for Trees and Shrubs is of relevance here (seeTable 1.1).

These specifications were developed in association with the Nursery Stock Industry and if adhered to by producers, and used by purchasers when specifying their requirements, should result in the production and supply of good-quality plant material.

Trees Outside the Standards

Some nurserymen specialize in the production of very small trees. In today’s tiny gardens these can be very useful and can take the form of the following:

•Top-worked trees. Some nurserymen produce trees where a rootstock is used to produce the stem of the tree and several scions are grafted on to the top to form a ‘top-worked tree’, e.g. Salix alba ‘Kilmarnock’ and Acer pseudoplatanus ‘Brilliantissimum’.

•Shrubs on a leg. A single stem of an often-vigorous, non-variegated form of a shrub can be taken up vertically and scions of an often special form of the same shrub grafted on top to form a very small tree, e.g. Euonymus fortunei ‘Emerald ‘n’ Gold’.

•Shrubs converted to small trees. A single stem of a shrub with enough vigour can be grown vertically up a cane. Once enough height is reached, the growing point is pinched out and the resulting shoots used to form the head of the tree. Examples of shrubs where this is often done are Buddleja alternifolia and Amelanchier lamarckii.

In the USA the situation is different. The Tree Care Industry Association (TCIA) produces a set of ANSI A300 Standards. These are not intended to be used as standards but should be used to develop written specifications for work assignments leading to established objectives and measurable criteria.

Euonymus japonicus ‘Bravo’ grown as a standard on a UK nursery.

A young plant of Amelanchier lamarckii having been pruned to form a multi-stemmed tree. Several shoots at the base of the plant were removed when very young and the plant encouraged to grow with just a few upward growing shoots.

The Use of Rootstocks in Tree Production

Rootstocks can be important in the propagation of trees and can influence greatly the subsequent performance of the tree.

Some trees just cannot be grown from seed. Some species cannot be relied upon to produce viable seed, or they may be hybrids that will not ‘come true’ from seed. Rootstocks can, in many cases, enable the commercial production of uniform trees with a predictable performance. This they may do by controlling the vigour and ultimate size of trees. Or they may shorten the time period between planting, and flowering and fruiting. Such considerations are very important, especially when considering fruit trees.

‘Treatment’ of the Roots of Trees or Shrubs

Trees and shrubs can be supplied bare root, root wrapped, container grown or containerised. All these terms have specific meaning within the industry. Each method has its own advantages and disadvantages.

Bare Root

The plant is lifted from the ground, any remaining soil shaken off and supplied as such. This is acceptable for deciduous subjects during their dormant season, but usually only where transplantation is going to occur within the same garden. Bare roots are extremely susceptible to drying out. Once the roots have dried out, the plant is as good as dead. After lifting, during transportation and during planting, the roots must be protected from drying out. The use of some form of polyacrylamide gel has been advocated. The gel is used in the form of a root dip, the gel forming a thin film over the roots, protecting them to a limited extent from desiccation and is also said to lower transplant shock. The shock of transplanting is said to be lowered by the gel holding water at a low tension, so that plant roots can penetrate the gel and adsorb water from the gel. Such a root-dip treatment could be used in addition to wrapping the roots.

Root Wrapped

Immediately the plant is lifted from the ground, the roots are wrapped with some material, usually hessian or a polythene bag, to protect and protect the roots from desiccation. This is good nursery practice for deciduous plants during the dormant season.

Container Grown

When this system is employed, the young plant is transplanted and grown on in a container until it is well established. When ready for sale or planting out, the plant roots should have thoroughly permeated the compost to the extent that the root ball does not disintegrate when the plant is removed from its container. Conversely, the roots should not be seen to have become severely limited by the edge of the container with the roots running round the edge of the compost forming a solid ring of roots. Such plants are known as ‘pot bound’ and are not desirable. Where the plants are pot bound, but only to a limited degree, teasing out the roots prior to planting will help alleviate this problem.

Containerised

This is said to occur where a bare-root plant is placed into a container just before sale. The roots have no, or very little, time to permeate the compost before sale or planting out. This can be done to extend the life of an otherwise bare-root plant before sale or planting out. Less reputably, plants can be containerised just before sale or to make the plant more presentable and, therefore, of higher value. In either case, this should be made clear to the purchaser or planter. Unless great care is taken during planting in to open ground, the loose compost will fall off the roots and the planter left with an exposed bare-root plant.

THE PRODUCTION AND SALE OF SHRUBS

In addition to the British Standard 3936, the British Container Growers Group, to which a large number of prominent UK nurseries were signatories, published a Specification of Standards for the Production of Hardy Container Grown Plants several years ago (an undated publication). This contained a definition of standards to which a range of container plants should be grown. Included in this were criteria such as container size, number of breaks and overall height, plus numerous other points for a wide range of plants. If adhered to, or at least considered, good-quality plants should be produced and supplied. Today, in practice, most good suppliers meet, and indeed exceed, these standards.

CHAPTER 2

TREES AND SHRUBS IN GARDEN DESIGN

Trees, and to lesser degree shrubs, are fundamental to the design of a garden or successful planting. They function on two scales: the overall design of a garden or landscape and, when planted together, form plant associations, which the designer should consciously plan to form aesthetically pleasing plantings. These two scales are here considered separately.

Acer palmatum ‘Wilson’s Pink Dwarf’ is a slow-growing plant that, when first planted, may function as a shrub, but eventually forms the dimensions of a tree in a small garden.

THE OVERALL DESIGN

Provision of Shelter, Privacy and Enclosure

Starting with an open, new site, trees can be used to create shelter, necessary on any exposed or windswept site, privacy and to produce a sense of enclosure. Here, selection of the best plant is vital to fit the space available. Far better to plant Thuja plicata ‘Atrovirens’ (Western red cedar) that will produce a thin, uniform, green, fine-textured hedge, rather than the ubiquitous × Cuprocyparis leylandii (Leyland cypress) that, unless a considerable volume of space is available, will rapidly become far too large and problematic for the garden owner and neighbour alike!

One of the two Red Borders at Hidcote Manor Garden. The tall, coniferous hedge forms a perfect, uniform, dark-green backdrop to the magnificent mixed border in front.

Backdrop

Trees can provide an excellent uniform backdrop upon which to display your carefully composed plantings. This backdrop can remain largely the same throughout the year, as is the case with evergreens, such as many conifers, or can change with the seasons, as exemplified by deciduous trees. A further variation can be created by using hedges of trees such as Fagus sylvatica (beech) and Carpinus betulus (hornbeam) whose growth remains in a juvenile condition when clipped and does not drop in winter. Hence, the backdrop has three seasonal changes: green in summer, golden brown in winter and light-green and fine-textured in spring.

Betula utilis subsp. albosinensis photographed in early winter. The pinkishwhite stem is clearly shown against the dark-green background of an evergreen coniferous hedge.

Division of Space

Within a garden or planting scheme, trees and shrubs can be used to block an overall view and divide the whole into a series of spaces. This can have several effects. The garden will feel larger than it actually is. By skillful positioning, the visitor can be guided around the garden and steered to see the best carefully contrived views. In the ancient scholar gardens of China, walls were often used to ensure that the visitor passed through a series of visual delights without appreciating how far he had walked or the over-all garden size: such an effect can also be created by the use of trees and shrubs to obscure the view.

Framing of Views

Again, the ability of trees and large shrubs to limit and frame views, both within and outside a garden, can be employed by the designer. Here care must be taken to select the correct tree or shrubs, considering their ultimate size, so that the view is framed, rather than obscured in time.

Mrs Winthrop’s Garden at Hidcote Manor Garden. Here the tall hedge separates this garden from the rest of the larger garden, providing Mrs Winthrop with the privacy she desired whilst sunbathing. The garden is hedged on three sides. The south side is left open to allow sunlight to flood in and create a suntrap.

Creating Vignettes

Small trees and shrubs can be used to create small spaces within a garden where a specially composed planting can be shown in partial isolation to the rest of the garden. This is exceptionally well demonstrated at Foggy Bottom the garden of Mr Adrian Bloom VMH.

Two plants of Thuja occidentalis ‘Degroot’s Spire’ partially isolating a planting of Crocosmia ‘Lucifer’s Match?’ in a mixed border at ‘Foggy Bottom’, the garden of Mr Adrian Bloom in Diss, Norfolk, England.

Three-Dimensional Planting

This is taking the idea of ‘see through’ planting to a higher level. It involves positioning a small tree or large shrub with a thin, largely transparent canopy near the front of a deep garden border, this having the visual effect of increasing the perceived depth of the planting.

A small tree of a Cytisus cv. at the front of a deep border. The viewer can see beyond to the planting at the rear of the border, thus making the border appear much deeper than it actually is.

Partial Views

Views within a garden can be partially or completely obscured by trees or hedges. When employed to partially block a view around a curving path, this can create a so-called ‘come hither effect’. All humans, gardeners especially, are curious creatures and when presented with a hidden view will inevitably wish to walk around the deliberate obstruction and see what lies beyond. This is frequently seen at Hidcote Manor Garden, a National Trust property in the Cotswolds.

Similar effects and a general lightening beneath trees can be achieved by controlled thinning of a tree’s canopy as the tree grows. This is well demonstrated at the famous woodland garden created by Princess Strada in Normandy.

Scale and Proportion

In this context, the word scale is taken to mean the relationship between a planting or garden and its overall situation. In the same context, the word proportion is taken to mean the relationship between the plants in a planting. In both comparisons, the concept of ‘visual weight’ is important, with a sense of balance wanting to be achieved in both.

The passing of time affects both these considerations. As time passes and as a planting develops, the relative sizes and visual weight of herbaceous plants, shrubs and trees alter. Herbaceous plants may be overgrown and disappear, and shrubs become proportionately smaller compared to the trees. Where one can watch a planting develop over years, this phenomenon may be observed. The originally well-designed planting developing into a pleasing, balanced composition.

PLANT ASSOCIATIONS

Here the designer and plantsman consider the fascinating area of plant associations. This being how one plant with its individual features relates visually with its neighbours. The designer needs to appreciate these individual plant visual features. These, plus any tactile or olfactory features, are described in detail for each tree or shrub profiled in this book.

When one considers aesthetics, ‘beauty lies in the eye of the beholder’, but this can be analysed to a large extent by objectively considering the visual features of plants. Trees can provide visual beauty from their overall habit, meaning their branch pattern, form, their three-dimensional shape and texture, plus in closer inspection, visual delight from their foliage, flowers, fruits, stem and bark.

Our olfactory sense can also be stimulated by the scent released from trees, be it the smell of a magnolia in full bloom or the pineapple scent released from the pressed foliage of Western cedar (Thuja plicata).

Tactile qualities of trees can also be employed to add interest in the garden, e.g. the smooth and shiny bark of the Tibetan cherry (Prunus serrula) or the papery, flaking bark of the paper bark maple (Acer griseum).

This section briefly considers each of these features.

Size at Maturity

Size at maturity is a feature of vital importance, and one that has been the object of much work in breeding and selection but is unfortunately difficult to predict accurately, particularly in the case of trees. The growing conditions a plant experiences greatly affect both the growth rate and eventual size of a plant. In this book, a size within a range is given, based on knowledge of the plant and given average, not exceptional, conditions. Very large trees, often called ‘champion trees’ of exceptional size, are not considered.

In some cases, tree size can be controlled by choice of rootstock. In ornamental trees this can be important with tree genera, including Malus (ornamental apples) and Prunus (flowering cherries). With trees intended to produce edible fruit, choice of rootstock is very important, since this can affect not only eventual tree size, but other factors such as the length of time taken between planting and the regular production of fruit. Many of these compact or dwarf selections are listed and described in Chapter 3.

Trees and shrubs can be reduced in size, at least for a period, by pruning and, where appropriate, such techniques as head raising, pollarding and coppicing are discussed (seeChapter 3).

Shape (or Form) and Habit

These are two visual aspects that are best considered together. Shape (or form) is self-explanatory and refers to the three-dimensional space or volume of space occupied. Trees and shrubs vary considerably in their shape, and this is exemplified by conifers (seeChapter 5 for this book’s selection).

How trees are propagated and produced in a plant nursery largely determines a tree’s future development and final shape. The variously shaped trees available from nurseries and how these may be employed is detailed in Chapter 1.

Habit (the branching pattern of a plant) is an important characteristic when considering compact plants for limited space. Many of the plants, especially the trees, profiled in this book have been bred or selected for their compact, freely branching, upright or sometimes fastigiate habits; such trees do not use much floor area but give height to planting.

In garden design and the subject of plant association, the relationship between form and habit of deciduous plants changes with the seasons. In winter, habit is very evident; in the other seasons, because of the presence of leaves, individual plant form or overall shape assumes greater importance.

Colour

It is in the use of colour, with each plant making its contribution, that the artistic flair of the designer can come fully to the fore. He or she can employ the full range of the colour wheel to create the vivid contrasts or subtle harmonies that the client may desire. Colour may be seen as a pageant flowing through the seasons, with each plant making its seasonal contribution.

A very strong colour contrast between the purple-red foliage of Physocarpus opulifolius ‘Diabolo’PBR and Choisya ternata SUNDANCE ‘Lich’.

In the recent past, much of this colour was provided by seasonal bedding schemes, which reached a peak in the case of wealthy Edwardians who used to favour spring, summer, autumn and winter bedding displays. Such displays required the production of ‘annuals’ under heated glasshouse conditions and much labour, often in the form of paid gardeners. Very few of us have access to these facilities and the resources for this form of profligate horticulture.

Flowering trees and shrubs provide colour, but often only for a short period of time. An aim of the breeder has been to extend this period, trying to induce the plant to produce a succession of bloom, rather than just a short display. In some cases, this has been successful.

Colour in the form of leaf variegation, not just green, but also shades of lighter green and white, has been sought by breeders very successfully. Both deciduous and evergreen shrubs with coloured leaves are widely available. Certain colour combinations provide the most vivid contrasts.

Another exceptionally strong contrast of foliage colours between Choisya ternata SUNDANCE ‘Lich’ and Veronica ochracea. These are both small shrubs easily accommodated in today’s small garden.

Some of these coloured-leaved shrubs provide even more opportunities by changing colour with the seasons. This might be both an opportunity and a problem for the designer!

In recent years, the length of winter has been more appreciated, perhaps because of its milder nature, and the need to provide colour and interest has been more fully appreciated. Here coloured-leaved evergreens have come to the fore. Approximately 20 per cent of evergreens was often recommended in the past as the best balance between evergreen and deciduous shrubs, a greater proportion being considered too ‘heavy’ and dreary. Today, with the advent of brightly coloured, compact evergreens, this percentage can be increased with great advantage. The fact that some of these coloured evergreens also have distinctive shapes, e.g. the numerous Phormium cultivars, adds to their versatility.

Shrubs such as this Phormium ‘Sundowner’ are now proving reliably hardy in many gardens and contribute vivid leaf colour and a dramatic habit all the year round.

A further gain is that the increasing mildness of winters allows the wider planting of shrub genera, such as Coprosma and Coryline, previously considered too tender for outdoor planting, but whose members contain many coloured-leaf cultivars.

Texture

In this context, texture relates mainly to shrubs and their leaves, but can also be noticed in trees as the leaves expand and develop through spring into summer. Do you recall a treescape in late spring? That beautiful diverse appearance is due to shades of green presented by the developing leaves, but also to their developing and differing sizes.

Texture can be considered as have having two components: one tactile, the other visual.

The leaves of Salvia argentea just compel you to touch them.

To consider the tactile component first, try to remember the leaves of lamb’s ears (Stachys byzantina) or Salvia argentea and compare those with the leaf of the Oregon grape (Mahonia aquifolium) when just emerged.

The new leaves of Mahonia aquifolium (Oregon grape) really are as slippery as they look!

Clients love to touch the soft ‘furry’ leaves of the salvia and watch water run off the waxen surface of the mahonia. The opportunity to exploit this experience is limited, but several shrubs do have strong textural features. For example, Viburnum rhytidophyllum, with its large, leathery leaves, whose veins are deeply surface-indented, and Rhododendron bureavii with dark-green, glossy leaves whose undersides are covered with a rich, woolly, soft to the touch, indumentum.

The large, entire leaves of Sorbus ‘John Mitchell’ are visually coarse-textured.

The second component of texture refers to the size and degree of division of leaves. A large-leaved shrub can be described as coarse-textured, e.g. Aucuba japonica. A shrub with many small leaves can be described as fine-textured, e.g. common box (Buxus sempervirens) or Veronica rakaiensis. The degree to which a leaf is subdivided will affect its appearance and texture: the broad, simple leaf of Sorbus aria (whitebeam) appearing coarser than the pinnate leaf of Sorbus aucuparia (mountain ash).

The subdivided, pinnate leaves of Sorbus aucuparia are, when compared to those of Sorbus ‘John Mitchell’, visually more finely textured.

Leaf texture and colour tend to interact and the plain-green leaf of Aucuba japonica ’Hillieri’, with plain, large, dark-green leaves, appears coarser than the yellow-spotted Aucuba japonica ‘Variegata’.

A further way that texture can be employed by the designer is to partially obscure or highlight a feature by acting as a backdrop. Consider a fine, garden vase mounted on a plinth. Against a fine-textured background, the vase is highlighted, against a coarse-textured background the vase is less distinct. Theory has it that the eye is distracted by the relatively large components of the coarse background and hence the vase is less prominent. Behind a large, domestic gas-tank would a fine or coarse-textured backdrop tend to hide it?

Fragrance, Aromas and Odours

A wide range of trees and shrubs emit scents or odours and would-be planters would be wise to acknowledge this and use these plants accordingly.

Trees within the genera of Magnolia, Malus, Prunus, Robinia and Tilia are notable for their fragrance. Many of these are compact and suitable for restricted spaces, where their scent may be confined and concentrated.

Whilst the flowers of Magnolia FAIRY MAGNOLIA BLUSH (‘Micjur01’)PBR are beautiful to look at, they are also deliciously scented. This is another factor for the gardener to consider when selecting plants for his or her garden.

Roses are, of course, well known for their scent, but note that not all are scented. The new garden roses, first bred by David Austin, are an attempt to combine the scent of old roses with the recurrent flowering of modern garden roses and, in many cases, to produce a more compact, better branched shrub.

Other shrub genera with scented flowers to have received the breeder’s attention and of note are the introduction of smaller, compact Philadelphus cultivars.

Various aromas and odours are released by many plants. Aloysia citrodora, lavenders and Cistus emit pleasant aromas when the leaves are crushed or, in some cases, just brushed by. Take care though – the author’s experience has revealed that what is loved by one is disgusting to another! Choisya ternata (the Mexican orange) is a case in point: liked by some, abhorred by others. The genus Salvia, the sages, needs particular care. Many members release a very bad smell when crushed (Salvia turkestanica being memorably bad) but Salvia rosmarinus (formerly Rosmarinus officinalis) is liked by all.

The foliage of Choisya ternata SUNDANCE (‘Lich’PBR). The bright-yellow foliage colour is appreciated by all, but the smell of the foliage, once touched, is liked by some but hated by others – gardeners be aware!

All interplay together, and the designer’s role is to select and plant to create pleasing creations for their client. Good designers earn their fees!

THE RELEVANCE TO OUR ENVIRONMENT

Pollution and climate change are now acknowledged problems. How can gardeners and designers help with these problems, given declining space? By employing modern, compact trees and shrubs selected for this role and detailed in this book, they certainly can. (Where appropriate, species or selections of British native trees and shrubs have been chosen and included in the plant profiles contained in Chapters 3, 4 and 5.)

In recent years there has been much debate as to whether we, as a nation of gardeners, should plant ‘native’ or ‘exotic’ trees and shrubs. The term ‘native’ in this context means naturally occurring within the country in which it grows or is planted. This is laudable, in that such planting will also help to increase all the other native animal species dependent on it for food.

Viburnum opulus (Guelder rose) photographed in early autumn when fruit colour, but leaf colour has yet to develop. This fine, deciduous shrub, native to the UK, is too large for today’s small garden, but the cultivar Viburnum opulus ‘Compactum’ is a much smaller, compact shrub, which flowers and fruits just as freely. A good example of where a gardener with a small garden may wish to plant a native plant to encourage nature conservation and can do so, but by careful selection can choose a smaller more compact plant more suitable for where space is limited.

From an aesthetic point of view this could, however, be questioned. For example, in the case of the UK, the country has a somewhat depauperate flora, due to the relatively recent last Ice Age, with only relatively few species. Planting with only native species could, therefore, result in a somewhat uniform and perhaps visually boring planting.

The use of a much wider planting range, using plants from all over the world, could result in much more visually exciting and pleasing plantings. Would these mixed plantings be as good for encouraging other wildlife? Our native insects and birds would not have met these plants before; could they adapt to feed on them? The Royal Horticultural Society (RHS) has done some experimental work on this subject (RHSorg.uk/plants4bugs). Native plants were found to be most favoured by insects, but exotics were still visited and useful, but to a slightly lesser extent. Probably the answer for gardeners is to steal an analogy from another context – ‘a little of what you fancy does you good’.

CHAPTER 3

DIRECTORY OF SUGGESTED TREES

ACER

A large genus composed of mainly deciduous trees. It ranges in size from large trees right through to shrubs and comes from all three northern continents.

Plants from the genus, known colloquially as ‘maples’, can be recognized collectively by useful common characteristics. They have buds arranged in opposite pairs that develop to give leaves also in opposite pairs. Their fruit is a winged samara (key) consisting of a nutlet or sometimes a pair and a large membranous wing. The wing is a mechanism for seed dispersal and in the autumn the whirling descent of the seeds delights children who frequently call them ‘helicopters’.

The leaves are often palmate, but not always so. Cultivated forms of Acer palmatum have been selected to have a very elaborate and often dissected leaf shape.

As a genus they have several characteristics that commend them to the would-be cultivator. Their leaf shape and the colours developed in the autumn are a major attraction. In some, the bark may be very characteristic and attractive, as with Acer griseum (the paper bark maple). In others, the bark may feature elaborate patterns or striations, as in the snake bark maples. The flowers of maples are usually a visually insignificant feature but, in a few cases, they may be especially attractive, e.g. Acer negundo var. violaceum looks very attractive in spring when in flower with its pendant, long, reddish-pink flower tassels.

Acer palmatum and its cultivars are considered collectively. The group of maples known as snake bark maples are also considered collectively. Acer griseum, the cultivars of Acer japonicum and Acer negundo ‘Flamingo’ are dealt with separately.

A mature tree of Acer griseum (paper bark maple).

Acer griseum (paperbark maple)

This species was first collected and introduced by Ernest Wilson, whilst he was plant hunting for the famous plant nursery Messrs Veitch, from Central China in 1901.

It is a slow-growing deciduous tree of outstanding beauty, which may eventually reach a height of 14m (40ft).

Usually propagated from seed, which is generally only 1–2 per cent viable, it is best grown as a half-standard or standard tree to enable the bark, which is the main feature, to be seen and closely inspected. Some seed variability is present and if purchasing a tree for use as a specimen, inspection of individual trees before purchase is advised, as some from a young age produce masses of peeling bark that hangs on the stem in loose flakes to reveal the cinnamon-red young bark beneath. In others, the bark does not exfoliate so freely, and this very desirable feature is less prominent.

The trifoliate leaf of Acer griseum showing autumn leaf colour.

In mid-spring the leaves expand to reveal delicate trifoliate leaves. The central leaflet is slightly larger than the two laterals and each has three to five pairs of serrations.

Small, inconspicuous flowers are followed by winged seeds, known as winged samaras, and are typical of the maples. The paired seeds hang down on stalks, each seed with its wing being 7mm (1¼in) long.

The branches of the tree divide naturally to form a rounded or slightly taller than wide, somewhat irregular but very pleasing shape.

Growing Requirements

Hardiness: USDA 7b/8a. RHS H5.

Shelter: Avoid very exposed or very windy positions.

Sun: Best in full sun or part shade, but not heavy shade, to ensure that an evenly shaped specimen develops.

The cinnamon-red bark of Acer griseum, so clearly shown in winter.

Autumn leaf colour of Acer griseum.

Soil: The tree will grow in any soil providing that it is well drained in winter but avoid planting in very dry or excessively well drained soils.

pH: The plant is not pH-sensitive, but avoid planting in very dry or excessively well drained soils.

Garden Design Considerations

A superb, slow-growing, small specimen tree, providing fine leaf texture in spring and summer, plus bright late autumn leaf colour. Also very desirable is the distinct and attractive winter bark colour and texture.

It is often best planted near a path or at the front of a border to allow close inspection and appreciation of the bark, and is grown as a standard to allow underplanting for other seasonal interest.

When used in a planting intended mainly for autumn colour, Acer griseum reliably provides orange and red colours, which harmonize easily, but the colour develops late and may be employed to extend the display.

Acer griseum associates well with other acers, especially Acer palmatum and its many cultivars. With careful selection of Acer palmatum cultivars, interesting contrasts of habit, form and leaf texture can be produced.

Acer japonicum(Downy Japanese Maple or Fullmoon Maple)

This is a native of Japan and Korea and has been cultivated in Japan for many centuries. It is distinguished from Acer palmatum by its larger leaves, 8–15cm (3–6in) across, greater number of lobes to each leaf, having seven to ten lobes and with soft, hairy leaf petioles. Acer japonicum forms a bushy deciduous tree seldom reaching more than 6–9m (20–30ft) high, but often the same width. In cultivation it is generally larger than most forms of Acer palmatum.

Growing Requirements

These are the same as for Acer palmatum and its cultivars to which the reader is referred.

Hardiness: USDA 6b/7a. RHS H6.

The two cultivars most commonly grown are Acer japonicum ‘Aconitifolium’ AGM and Acer japonicum ‘Vitifolium’.

Acer japonicum ‘Aconitifolium’ AGM

Height: 4–8m (13–26ft).

Spread: 4–8m (13–26ft).

The leaves of this cultivar are deeply lobed and cut, and as the specific epithet suggests, resemble those of many Aconitum species, commonly known as monkshoods or wolfsbane. Attractive, small, red flowers hang down beneath the branches in spring. Leaf colour is green during the growing season, but reliably develops rich autumn colours of reds and deep-purple.

Leaves of Acer japonicum showing early autumn leaf colour, plus a pair of winged samaras (seeds).

The dissected leaves of Acer japonicum ‘Aconitifolium’ showing the development of the wonderful autumn leaf colour that is such a feature of this cultivar.

Acer japonicum ‘Vitifolium’

Height: 2.5–4m (8–13ft).

Spread: 2.5–4m (8–12ft).

The leaves of this cultivar are more divided than the species having ten to twelve lobes, the specific epithet suggesting a similarity to those of a vine. The leaves are green during spring and summer, but reliably develop rich autumn colours.

Garden Design Considerations

As these two cultivars are taller and wider than most A. palmatum cultivars, they can be usefully employed as backdrops to these and are also an excellent choice where a specimen bush-like small tree is required and adequate space is available to accommodate their spread.

Acer negundo ‘Flamingo’

A variegated cultivar of Acer negundo, the box elder, which is native to North America.

Acer negundo ‘Flamingo’ is a fast-growing, medium-sized, deciduous tree capable of attaining a height of 12m (39ft) and a width of 8m (26ft). It is recommended here only for growing as a shrub, the growth being cut back hard every second year in late winter. When grown in this manner, the pinnate foliage is larger than normal and the variegated foliage more prominent. Each leaflet has a green centre, splashed with pink when young that later turns to cream. When cut back as recommended, the upright stems achieve a height of 2–3m (6½–10ft) and the brightly variegated foliage is well displayed.

In winter, once the foliage has fallen, the young, pale-grey stems add to a coloured winter stem display.

Growing Requirements

A plant of easy cultivation.

Hardiness: USDA 6b/7a. RHS H6.

Aspect: The growing situation can be of any orientation.

Shelter: No extra shelter is required.

Sun: Full sun or part shade.

Soil: A soil of any texture will suffice providing that it is well drained.

pH: It is not pH-sensitive, tolerating a wide range of soil acidity or alkalinity.

When cut down hard every other year it is recommended that the plant receives an application of balanced fertiliser and is mulched every spring to encourage the rapid new growth required.

Any sign of ‘reverted’ all-green growth should be removed as soon as seen. Reversion will occur, is much more vigorous than the desirable variegated growth and will soon dominate the growth unless rapidly removed.

Garden Design Considerations

This cultivar, when grown as a coppiced tree, provides light, bright foliage colour for the summer garden and pale-grey winter stems. Although of rapid growth, it does have a high-maintenance requirement if it is to be displayed to best advantage.

The brightly variegated foliage of Acer negundo ‘Flamingo’ in early summer.

Acer negundo ‘Winter Lightning’ pollarded to develop and display the light-coloured stems clearly in winter.

Acer palmatum (Japanese Maple)

This species is native to Japan, China and Korea.

When grown from seed, this species can produce very variable seedlings. The trees can be 6m (20ft) high and wide at maturity; indeed, in wild populations they are often larger than this. At the other end of the range, true dwarf trees may occur that never exceed 1m (3ft) at maturity.

Features such as leaf colour and leaf shape tend to be characters that influence final size. Trees with the normal palmate five to seven lobes and plain-green leaves tend to be the most vigorous and attain the greatest size. Any change in leaf pigmentation – be it paler green, yellowed or reddish, or other variegation – tends to result in a reduction in vigour. The leaves can show a greater number of divisions than normal and the more the leaves are divided, generally, the greater reduction in vigour. The habit of the plants raised from seed can occasionally be very upright or pendulous.

This apparent natural variation has been selected for by growers, especially in Japan, over millennia. This has resulted in the naming of several hundred named cultivars. In an attempt to categorise, the cultivars are attributed to Group names following the scheme laid out in Vertrees, J.D. & Gregory P. (2010) Japanese Maples: The Complete Guide to Selection and Cultivation.

The Groups are:

•Amoenum Group: leaf lobes shallowly to moderately divided, usually up to two-thirds of the way to the leaf base.

•Palmatum Group: leaf lobes moderately to deeply divided two-thirds to three-quarters of the way to the leaf base and, in some cases, almost to the base.

•Matsumurae Group: leaf lobes mostly very deeply divided more than three-quarters of the way to the leaf base.

•Linearilobum Group: lobes narrow, straplike, divided to the leaf base.

•Dissectum Group: leaf lobes very deeply divided and deeply dissected into sub-lobes.

•Dwarf Group: cultivars whose mature height does not usually exceed 2m (6½ft).

Growing Requirements

Hardiness: Care needs to be taken when selecting cultivars. Most are USDA 6a/7a RHS H6, but some are USDA 7b/8a RHS H5. When grown in the ground, the top growth of Acer palmatum, if fully dormant, has been found to be hardy down to –18°C (0°F). In very cold climates, the roots and top growth of plants in containers must be given some cold protection. Wrapping the entire container and plant in several layers of bubble wrap should suffice. It is important to remember that Acer palmatum in the wild is often an understorey tree, growing beneath the canopy of larger trees.

Aspect: In cultivation, the aspect of the site can be south-, west- or east-facing, but preferably not north-facing.

Shelter: In all cases, some shelter will be required. The amount of shelter required by an individual plant can largely be predicted by the plant’s leaf shape. The more the leaf is dissected, the more shelter will be required. Plants from the Linearilobum and Dissectum Groups have a particular need for shelter from wind. An east-facing site should be treated with caution. Acers are susceptible to late spring frosts, especially if the frost is followed by strong, early morning sunshine, as is often experienced in a site open to the east.

Sun: Providing that a regular water supply can be maintained throughout the growing season, then green-leaved cultivars will grow well in full sun and purple-leaved cultivars will develop their characteristic coloration more clearly. Care must be taken because any interruption in water supply, or excessive drying winds, will result in scorching of the leaves. Pale and yellow-leaved cultivars require careful positioning since stronger light produces better coloration, but too much light will result in scorching. Growing the plants below taller deciduous trees that provide dappled shade is often optimal for nearly all cultivars.

Soil: An organic soil that is well drained but retains water in the summer and with an acid pH is ideal. Not many gardeners have this ideal, and this maple can be very successfully grown in soils that deviate from this. A sandy, clay or loamy soil is acceptable, providing that it is well drained and retains moisture in summer. The addition of organic matter will improve the structure and moisture retention. Mulching the ground with organic material after planting and thereafter on an annual basis will help the plants to establish and will gradually improve the soil.

pH: Soil pH should ideally be between 5.5 and 6.5 and not above pH 7. Thin, alkaline, chalky soils should be avoided.

Garden Design Considerations

Acer palmatum, including its numerous cultivars, has an exceptional range of applications in the garden and landscape.

TABLE 3.1  ACER PALMATUM CULTIVARS

From Table 3.1 it is clear to see that there is a considerable range in size of plant involved from moderate-sized trees to small, compact shrubs, and careful attention to this feature is necessary during the process of selection. Their need for at least some shelter could limit the use of these trees, although the larger cultivars with uncut leaves can be used to shelter those with more delicate, finely cut leaves.

In many gardens, the need to create the correct conditions for these trees to thrive can be clearly seen – larger trees being planted and left to develop a dappled, sheltered environment beneath them. This can be seen in both the Acer Glades at the Westonbirt Arboretum in Gloucestershire, England. The Old Glade is surrounded by a very diverse planting of trees and shrubs, all of which serve to provide the necessary environment. The Acer Loop in the younger part of the arboretum, known as Silk Wood, is a more recent creation with a range of quick-growing Larix (larch) employed to rapidly produce a lightly shaded woodland in which a collection of Acer palmatum cultivars grow to perfection.

Acer palmatum cultivars growing under the dappled deciduous shade of Larix sp. (larch) in Silk Wood, part of Westonbirt Arboretum Gloucestershire, England. This represents almost ideal growing conditions.

Within the correct environment, a range of garden design techniques can be employed to effectively display these choice plants. Taller plants can be used to act as a backdrop to their small companions and maples of differing habits placed adjacently to emphasise their differences. The height, but not width, of some cultivars can be increased to create the desired effect. Acer palmatum cultivars of the Dissectum Group usually are pendulous in habit, forming, when left to their own devices, a flowing mound of growth. If desired, a strong shoot can be trained up a cane and once the desired height is reached, the leader allowed to droop naturally. Followed by further careful formative pruning, this will result in a fountain, rather than a mound, of fine-textured pendulous growth.

The colour and texture of the maple’s leaves are perhaps the most important visual features. Autumn leaf colour is the characteristic that first comes to mind, as some cultivars are legendary in their ability to produce amazing, vivid, autumnal displays. Many cultivars show changes in leaf colour from spring, through summer and into autumn. In addition, these colours can be readily predicted, especially with regard to final autumn leaf colour. The garden designer must, therefore, have a good ‘eye for colour’, considering the kaleidoscope of colour that can be presented to the garden viewer throughout the changing seasons. Fiery autumnal displays can be created with the strongest reds and yellows, although some of the most effective plant combinations employ the contrast between one blazing plant against the solid dark-green of a non-coloured cultivar.

In addition to leaf colour, the maples add leaf texture to the garden designer’s palette. The basic five-lobed leaf of the original Acer palmatum is fine-textured compared with other trees and shrubs with much larger, simple leaves and coarser texture. Maples can be used against these coarser textures to create various degrees of textural contrast or, for a more subtle effect, planted as a small group with each Acer palmatum cultivar displaying a different leaf texture. The most accomplished designers enjoy a heady but planned mix of all the visual features maples display!

Late autumn and winter are other times when these maples can bring interest and, in some cases, drama to the garden. The black silhouette of sinuous acer branches against a reddening afternoon winter sky can certainly be stunning. A few Japanese maples have strongly coloured bark, e.g. Acer palmatum ‘Sango-kaku’ (the coral bark maple). In these cases, this colour is most apparent once the leaves have fallen and the tree should be positioned so that any direct winter sunlight falls upon and highlights this feature.

Acers create a strong oriental feel to a garden and can be used with other associated plants, such as conifers and bamboos, together with other appropriate features to create a Japanese- or Chinese-styled garden. In such gardens, the acers are often used as specimens to bring seasonal vivid colour to gardens otherwise noted for a very restrained use of colour.

As if this was not enough, maples are also widely used in container gardening where their slow growth, compact habit and small eventual size are all advantages. In the Japanese art form of bonsai (the word literally meaning plant in a pot), the beautiful features of acers already discussed are developed and cultivated on an individual and miniature scale. Many different types of tree and shrub can be used to form a specimen bonsai, but maples are very often chosen. In China, the ancient skill of penjing is still widely practiced, but here it is a miniature landscape that is created and maintained. Maples frequently feature in these miniature words.

Japanese maples with all these diverse attributes should surely form an important component in today’s increasingly compact or small gardens.

A strong contrast of both leaf colour and texture. Rheum palmatum, an ornamental rhubarb, growing next to Acer palmatum ‘Dissectum Atropurpureum’.

Acer palmatum ‘Orange Dream’. Photographed in early spring just as the leaves were expanding.

Acer palmatum ‘Orange Dream’. Photographed a little later that spring. Note the leaf expansion and change in leaf colour.

Acer palmatum ‘Orange Dream’ showing autumn foliage colour. These changes in leaf colour through the seasons is but one of the joys of growing acers.

Acer palmatum ‘Skeeter’s Broom’. A dwarf cultivar with excellent autumn leaf colour.

The red bark of the younger stems of Acer palmatum ‘Sangu-kaku’ (coral bark maple). This cultivar has light-yellow autumn foliage colour and can grow to make a tree 10m (30ft) tall.

Acer palmatum ‘Koto-no-ito’ of the Linearilobum Group. In cultivars such as this, the leaves are divided into fine, linear lobes. They need sheltered conditions if they are to grow well.

Snake Bark Maples

Acer davidii is perhaps the most widely cultivated and typical of this group of acer species. In the wild, Acer davidii is a deciduous small-to medium-sized, round-topped tree, still quite commonly found in central and western China. The species has been introduced into cultivation several times and has been found to be quite variable, making a tree between 9 and 15m (30–50ft) high. The leaves, although sometimes lobed when young, are normally undivided, 7.5–13.5cm (3–7in) long, heart-shaped at the base and unevenly toothed.

The main points giving this species great ornamental value are well-developed autumn leaf colour, plus green and white striated bark.

TABLE 3.2  SNAKE BARK MAPLES AND CULTIVARS

Growing Requirements

Hardiness: USDA 7b/8a RHS 5. Except Acer capillipes and Acer pensylvanicum ‘Erythrocladum’, which are USDA 6b/7a. RHS H6.

Aspect and shelter: For all species and cultivars mentioned in Table 3.2, the site can be facing any orientation, but it must be sheltered, especially from cold north or easterly winds.

Sun: Full sun or part shade is acceptable, and they can be used to provide the necessary dappled shade required by the less tolerant Acer palmatum and its cultivars.

Soil: The soil can be of any texture, but it needs to be well drained, fertile and moisture-retentive. A thin, excessively well-drained soil that dries out in summer should be avoided.

pH: All the snake bark maples mentioned in Table 3.2 are tolerant of a wide pH range, with the single exception of Acer pensylvanicum ‘Erythrocladum’, which requires a neutral or acidic soil.

Garden Design Considerations

All the trees in Table 3.2, except Acer pensylvanicum ‘Erythrocladum’, make superb specimen trees. Ideally, they should be positioned where the bark striation, young growth and buds can be inspected closely and appreciated, especially in the winter. They provide several seasons of interest, being shapely trees, having small, often pendant inflorescences in spring, attractive summer foliage and, in most years, very bright, autumn leaf colour.

Those grown as multi-stemmed trees or cut down hard every other year in late winter are good stand-alone plants contributing vivid autumn leaf and winter-stem colour. They are also good contributors to a winter garden or border, being a little taller than Cornus coppiced for winter-stem colour.

The fine, white striations on a green background make a clear pattern on the bark of Acer capillipes.

The young red stems of Acer davidii ‘George Forrest’. As the branch ages and its bark develops, the pattern changes to white striations on a green background.

The younger red stems of Acer × conspicuum ‘Phoenix’ will gradually change to a yellow bark as it ages.

Acer pensylvanicum ‘Erythrocladum’. Here a young branch shows the typical pink bark colour. The yellow autumn foliage colour is also shown.

Acer davidii VIPER (‘Mindavi’). Here an older branch with white striations on a green background is shown.

ALBIZIA

A genus of about 130 species of deciduous trees, shrubs and climbers from Asia. They have pinnate foliage resembling mimosa and fluffy heads of flowers. Only Abizia julibrissin is cultivated in temperate areas. The species and its cultivars are widely cultivated in the USA, but in south-eastern parts it has become an invasive weed and should not be planted.

Growing Requirements

Hardiness: USDA 7b/8a. RHS H4.

Aspect: A south- or west-facing site should be selected.

Shelter: A warm, sheltered site is required, away from cold winds.

Sun: Full sun is required for best growth and flowering.

Soil: A soil of any texture is acceptable, but it must be well drained.

pH: