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- Herausgeber: The Crowood Press
- Kategorie: Geisteswissenschaft
- Sprache: Englisch
This beautiful book explores the world of colour in the plant kingdom and introduces the artist to effective practical methods of using colour in botanical painting. It focusses on the relevance of making accurate observations of colour in botanical specimens and recognizing the value and importance of using colour theory to achieve successful results. With over 500 images, this elaborately-illustrated guide uses the author's finished artwork, diagrams, and step-by-step tutorials to explain the important role of colour in this compelling genre. This book is a must for all aspiring botanical artists, illustrators and students.
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Seitenzahl: 323
Veröffentlichungsjahr: 2021
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COLOUR
for BOTANICAL ARTISTS
and ILLUSTRATORS
Pulmonaria saccharata ‘Mrs Moon’. (Leigh Ann Gale)
Leigh Ann Gale
COLOUR
for BOTANICAL ARTISTS
and ILLUSTRATORS
First published in 2021 byThe Crowood Press LtdRamsbury, MarlboroughWiltshire SN8 2HR
This e-book first published in 2021
© Leigh Ann Gale 2021
All rights reserved. This e-book is copyright material and must not be copied, reproduced, transferred, distributed, leased, licensed or publicly performed or used in any way except as specifically permitted in writing by the publishers, as allowed under the terms and conditions under which it was purchased or as strictly permitted by applicable copyright law. Any unauthorised distribution or use of this text may be a direct infringement of the author’s and publisher’s rights, and those responsible may be liable in law accordingly.
British Library Cataloguing-in-Publication DataA catalogue record for this book is available from the British Library.
ISBN 978 1 78500 940 2
Cover design: Sergey Tsvetkov
DEDICATIONThis book is dedicated to my husband Rupert for his unending love, support and encouragement in all that I do.
Contents
Preface
Colour is all around us in our everyday lives. Unless we specifically choose a set of colours for a particular purpose – such as an interior decorating scheme, maybe an outfit to wear or a planting scheme in a garden, for example – it is something that most of us tend to take for granted and experience passively. Throughout man’s existence, colour has always been a powerful means of communication, from the earliest cave paintings produced thousands of years ago to the modern-day use of colour psychology in advertising campaigns. There is always a message to be relayed whenever colour is experienced.
Rosehip of Rosa rugosa.
Having pursued an early career in the visual arts as a graphic designer, I witnessed how the use of colour can be at the forefront of visual communication, and now, as a botanical artist, I am fascinated by the way in which plants use colour to communicate and by how best I can use colour in my own painting.
The role of colour within the plant kingdom is primarily for communication with pollinators for the purposes of reproduction, but colour also plays a significant role in helping plants to survive and evolve. Plants are static. They must rely on being able to adapt themselves to their growing environments, and using colour is one way they can do this. For example, some plants use variegation in their foliage, which maximizes the amount of light they receive to ensure healthy growth. Some grow special silvery hairs on their foliage and stems to reflect bright light and retain moisture when conditions are too dry. The simple process of being able to produce the green pigment chlorophyll, when combined with light, is something that most plants do so that enough food can be produced to sustain long-lasting growth. Plants can and do use colour in the most innovative ways.
The purpose of botanical illustrations is also to communicate – when it is essential that floral species are recorded accurately for the purposes of identification – and a major part of this can be done by using colour. Artists who produce their botanical artworks in colour need to fully equip themselves with a comprehensive understanding of colour science, but they also need to know how to use colour knowledgeably in a practical way. Colour matching to specimens, mixing coloured pigments, painting techniques, and so on, are all necessary skills to be used effectively and creatively in botanical painting.
This book sets out to provide botanical painters of all abilities with a toolkit of facts, theory and practical knowledge about colour, all of which are essential for producing well-informed, accurate botanical paintings. It addresses the role of colour in a botanical context entirely: from understanding why and how colour is used in the plant kingdom and identifying colour palettes within botanical specimens, to selecting appropriate watercolour pigments to mix and practical exercises to complete. The chapters within this book, I hope, will provide you with a full and useful reference about colour for botanical art and illustration.
Introduction
Learning about colour is usually introduced into mainstream education during the early years when basic colour mixing is taught. Children may explore and enjoy painting at a young age and the science of colour may be introduced in later school years. Some young people will expand on this font of basic knowledge and continue into careers in the art and design industries, but for many this will be the extent to which they learn about colour during their lifetime.
For those who come to botanical painting later in life, it is often this foundation of colour knowledge from school that is called upon. Some can recall the colours of the spectrum and how to make secondary colours from primary colours – which is of great benefit – but this can sometimes be where their practical knowledge ends. Artists who are to produce accurate and aesthetically pleasing botanical paintings will require a deeper and much more extensive understanding of colour, which will prove to be a major attribute at every stage in the process of botanical art and illustration.
Clematis tangutica. (Leigh Ann Gale)
As a botanical illustration tutor, I often witness the sheer delight and amazement that my students experience when they notice for the first time that the many different colours they may see in a botanical specimen are, in fact, purely mixes of, say, just three or four colours. It is only then that they realize they won’t need to use every colour in their watercolour palette to mix the colours they can see. To me, this represents an almost passive extension of the basic colour theory lessons my students learned in school, when they start to notice, explore and analyse colours in much greater detail. These discoveries are also proof that accurate observations of colour in plant specimens are such an important and necessary part of the illustration process, even before any painting can take place. Chapter 1 in this book, therefore, explores the vast topic of colour in the plant kingdom, and analyses exactly why and how plants are coloured the way they are.
For those artists who have little or no recollection of lessons about colour in school, it is useful to learn some of the fundamentals of colour science. Most have seen beautiful rainbows in the sky, but just what causes those spectrum colours to appear? Basic colour theory is addressed in Chapter 2, which asks ‘What is Colour?’ – how do we see it and perceive it, and how do we use it in our everyday lives? In an artistic context, too, explanation is given about subtractive colour mixing (the physical mixing of coloured pigments), the attributes of the artist’s colour wheel, and how colours harmonize.
The tone of these first two chapters sets the scene for introducing colour in a much broader, practical context. Firstly in Chapter 3, watercolour pigments are explained and topics such as the technical properties, definitions and vocabulary associated with watercolours are discussed, together with how to create a botanical watercolour palette. Secondly, in Chapter 4, the all-important process of identifying colours in specimens is addressed, and appropriate watercolour selection, mixing and matching are taught. This full analysis represents the pinnacle of the whole process of using colour in botanical painting: suggesting a physical transition between what the eye sees and what the hand produces.
Chapter 5 provides insight into how best to use colour in botanical painting from an artistic point of view: considerations about the placement, distribution and balance of colour; using colour to help describe the three-dimensional properties of botanical structures; and painting techniques are all suggested.
The remaining two chapters offer students and those with some experience of botanical painting an opportunity to practise some useful skills and painting techniques. Chapter 6 focuses specifically on a variety of painting challenges that may occur from time to time, such as creating the translucent effect of the membranous layers between botanical components, painting variegated leaves, and producing the illusion of a metallic effect on foliage. Each ‘challenge’ is fully investigated, questions are asked about when each might occur, and suggestions are offered about how each might be tackled. A palette of suggested colours to use and a step-by-step painting process accompanies each challenge.
Finally, the painting tutorials in Chapter 7 allow painters to experience what it might be like to work through a real job, when considerations relating to colour need to be included at every stage of the illustration process and not just in the final painting. Each tutorial incorporates colour analysis from a visual, scientific and artistic perspective. A suggested colour palette and a step-by-step method are given for each topic, and the tutorials run through the spectrum colours sequentially. Tutorials are also provided at the end for painting black and white subjects.
Colour harmony of violet.
Rhododendron oldhamii. (Leigh Ann Gale)
The content of this book has been designed so that colour at every stage of botanical painting is explored. This should give those new to the subject a complete and thorough theoretical and practical experience and, for all, a progressive and logical route through what is hoped will be a useful reference source, enabling you to produce purposeful, scientifically accurate and aesthetically pleasing botanical paintings.
CHAPTER 1
Colour in the Plant Kingdom
Throughout the world, flora (or plant life) exists in groups categorized usually by region. These regions – otherwise referred to as ‘floristic regions’ – are further categorized into distinct habitats that we are more commonly familiar with, such as tropical, temperate, forest, desert, etc. Among these rich, diverse habitats lie different groups of plants: those that may be indigenous to the region, known as native flora; species deliberately grown by man, which include agricultural and horticultural flora; and weed flora, those species considered undesirable or invasive.
Autumn Tints. (Leigh Ann Gale)
One of the most common visible features among all floral species is colour. Whether it is a humble buttercup growing on the roadside bearing its bright sunny yellow flower, or the most unusual of colours such as the turquoise blue of the exotic Jade Vine (Strongylodon macrobotrys) native to the tropical forest of the Philippines, virtually every species exhibits colour.
Buttercups are among many wild flowers bearing yellow flowers.
The Jade Vine (Strongylodon macrobotrys) exhibits an unusual turquoise colour.
Living plants bear colour pigmentation, the substances produced biologically resulting from selective colour absorption from light. For the botanical painter this means that the recognition of colour in flora is highly significant. Accurate colour matching and mixing of pigments must take place during the painting stage in the artist’s preferred medium to capture a true likeness of the colours of a species. Many plants contain the green pigment known as chlorophyll, which is the primary pigment in the floral kingdom, but other coloured pigments are produced among species that attract pollinating insects to flowers for the purpose of reproduction or to warn of danger, for example.
Strelitzia reginae. (Leigh Ann Gale)
The world of colour present in plants is vast. Colours from the entire colour spectrum exist among the whole plant kingdom, some more commonly than others, and some extremely infrequently. Here we will investigate this world of colour in flora, thinking about common and uncommon colour groups, the existence of ‘black’ and ‘white’ in nature, how colour alterations take place, and how and why some plants exhibit variegation and pattern. These considerations are all important to the botanical painter, who needs a fundamental understanding of colour in flora.
CREATING AN AWARENESS OF COLOUR IN FLORA
The production of a botanical painting involves many processes, from observational drawing at the very beginning, through composition, and finally painting. It is normal practice to consider the colours of your specimen early on, usually during the drawing process while observing living specimens. This is when the colours are at their best. The colours you see will be at their freshest and most authentic in natural daylight, as if the specimen were still attached to the plant. It is always advisable for botanical artists to mix and match these correct colours from the palette and add them as painted swatches into a sketchbook, alongside pencil drawings and observational studies, before any final painting takes place.
Practise mixing and matching colours to your botanical specimens and recording them alongside your drawings in a sketchbook.
Recording colours in specimens accurately is fundamental to the art of botanical painting, in very much the same way as using appropriate painting techniques is to complete a painting. Sometimes, however, this can easily be overlooked, perhaps through lack of skill, practice or patience, which can be to the detriment of the painting in the long run. Observation and recording of colour at the initial stages of a project will always ensure you have captured a true likeness to the colouration of your subject matter when ideally it will be at the peak of its growth. Similarly, it is understandable that students and amateurs may not necessarily notice subtle variations in hue on a leafy specimen of camellia, or the subtle changes in shades of yellow in a flag iris flower, for example, unless the colours are noted. With practice, however, these skills can be acquired and used later in the painting process.
WHY ARE PLANTS, FLOWERS AND FRUITS COLOURED?
A good majority of plants, at least in some part of their composition, are green – green leaves and green stems, for example – but many plants and flowers contain additional colour pigments, especially in the petals of flowers. Sometimes the leaves themselves may be the colourful part of a plant, perhaps displaying some variegation or patterning, or contrasting with small insignificant-looking flowers that may be less colourful. Additionally, we observe pigmentation in other structural components, such as the flower stems, bulbs and roots, as well as fruits and seeds, all of which may contain the same pigments as the flowers.
More often than not, it is the flowers themselves that are the most colourful structures of a species, primarily for reproductive purposes. Plants are static, they are unable to move around to seek out suitable pollinators and so they must do their utmost to attract them by other means. Attractive-coloured flowers are the solution, especially for those plants that rely on airborne insects and birds for pollination. These plants may also offer sweet nectar rewards, further enticing pollinators to visit and revisit them.
Colour distribution is evident in different structures of plants.
The tops and bottoms of gladioli corms exhibit colouration that may be indicative of forthcoming flower colours.
Lilium Bulbs. (Leigh Ann Gale)
The brightly coloured flowers of Lantana camera are attractive to pollinators.
Beautifully coloured hibiscus flowers are pollinated by insects and birds.
The heavy scented Philadelphus coronarius ‘Aureus’ is inviting to bees.
The red berries of Arum maculatum are toxic to humans but particularly favoured by pheasants.
Eye-catching red and white spotted caps of the Fly Agaric mushroom (Amanita muscaria) are highly toxic to humans but enjoyed by slugs and red squirrels.
Fruits of plants, especially, may also be highly coloured. For example, berries during the winter months may attract birds or animals to eat them, which in turn can aid the dispersal of seed. However, brightly coloured berries can also signify danger: toxicity within the fruit, which if eaten could be fatal. As humans we have learned over the centuries to recognize which fruits and berries are harmful to us, and birds and animals have done the same. It is certainly the red berries that we treat with caution. In life we associate the colour red with heat and danger; warning signs are often displayed containing the colour red, and when travelling we use a red traffic light informing us to ‘stop’. In nature we learn to treat red berries with caution, noting their potential toxicity, for example the fruits of black bryony, cuckoopint and yew, which if eaten will cause us harm. Similarities can be drawn with fungi too, for example the beautiful but toxic red and white spotted cap of the Amanita muscaria (Fly Agaric) mushroom and the bright red Russula mushroom.
ALTERNATIVE METHODS OF ATTRACTING POLLINATORS
Colour alone is not necessarily the only attraction to pollinators. They are often enticed to a flower in anticipation of a reward, most commonly nectar and pollen. A combination of colour and a reward offer serves as a ‘come and visit me’ message from the plant and an invitation to the pollinator to revisit another time. Additionally, there may be other factors that help encourage pollinators to visit plants, such as scent and purposely-shaped botanical structures. For example, bees are attracted to very colourful, sweet-smelling flowers, moths are attracted to sweet-scented white or pale flowers such as gardenia and jasmine that open in the evening, and butterflies are attracted to long tubular flowers from which they can retrieve a nectar reward using a long proboscis.
Butterflies use a proboscis to reach the sweet nectar rewards of buddleia.
Colour to attract pollinators for reproduction
For plants to survive and reproduce, they may use colour in similar ways to animals and birds – for attraction. The process of reproduction in flora begins with the attraction of the correct type of pollinator to a species. Plants that rely on colour to attract winged pollinators, for example, rely on being able to invite them by making their flowers clearly visible, attractive and accessible. This is often done by displaying their colours when they are at their richest and most intense. Once a winged pollinator visits a flower, pollen is transferred onto its body and wings; a nectar reward may be taken, and the pollinator will leave the flower to move onto the next. As the pollinator moves from flower to flower, the transferral of pollen takes place and pollination occurs. If successful pollination and fertilization of the ovules has occurred, then the job of the colourful corolla (petals) will have served its purpose, the flower will fade and wither, and may sometimes fall away from the plant. This withering process signals to oncoming pollinators that these flowers do not need to be visited because pollination has already occurred, allowing them to conserve energy to visit only flowers that remain colourful and open for pollination. The pollination process of flowers also triggers the plant to expend energy into producing vital fruit and seed to enable it to reproduce.
Once flowers have been visited by insects, they will wither and fade if pollinated successfully.
COMMON COLOURS IN PLANTS AND FLOWERS
Among the abundance of colours we see in flora, a vast majority of flowers and plants contain specific pigments for the purpose of alluring pollinators: reds, pinks, purples, violets, oranges and yellows are among the most common of colours. There are several different pigments responsible for creating groups of colours, of which chlorophyll is the most common. Additional pigment groups include anthocyanins, carotenoids, flavonoids and betalains.
Chlorophyll (green pigment)
Out of all vegetation, the most commonly occurring colour is green. When we view a picture of our planet taken from space, we see dominant colours of blue, brown and green, depicting the sea and sky, rock and desert, and the vegetation on land. Green leaves, green stems, green grass – green is perceived as the most noticeable colour in our gardens, in open spaces such as parks and woodland, and along river-banks and verges. Plants appear green because they contain large quantities of chlorophyll. Chlorophyll is capable of absorbing light in the red (long) and blue (short) wavelength regions of the visible light spectrum that the human eye can see. Green light is reflected rather than absorbed, therefore making vegetation appear abundantly green.
Chlorophyll is the most common pigment seen in vegetation.
Foliage is predominantly green in the plant kingdom.
The hollow stems of bamboo (known as culms) are green before ripening and prior to being cut as garden canes.
Green chlorophyll pigment in variegated foliage sometimes forms stripy patterns.
The unusual green-coloured flower of Deherainia smaragdina (‘Dog Mess Flower’) relies on its aptly named pungent scent to attract its pollinators.
Most plants, trees, and shrubs contain chlorophyll in their foliage in varying quantities and intensities. Sometimes, however, leaves may also contain additional pigments that produce other colours, such as red and purple. When this happens, such multiple-coloured foliage is known as variegation.
There are a few flowers that contain chlorophyll, such as species of the Euphorbia family and others. This phenomenon is quite unusual, as colourful flowers are generally required for the attraction of pollinators. In plants that contain green flowers, however, it is likely that another part of the plant facilitates the attraction of its pollinators, such as the leaves, a strong scent or perhaps a particularly sweet nectar reward.
OTHER PIGMENTS IN COLOURS
Besides the green pigment chlorophyll, our natural world is full of many other colours too, providing us with a rich visual display that we tend to take for granted all year round.
We have learned that flowers in particular have evolved alongside their pollinators, and their use of colour pigmentation has become one of the defining features of their ability to reproduce. From the wealth of colours visible to us, it is often the floral and reproductive structures (petals, stamens, stigmas and styles) that are the most striking and colourful to catch our – and the pollinator’s – eye.
It is also interesting to notice how groups of colours – and therefore, pigments too – may be seasonal. For example, during spring in late April and May we see carpets of bluebells in our woodlands, the delicate blue flowers of forget-me-nots, and spires of the blue-violet flowers of common bugle growing in rapidly spreading clumps, and by early summer in June and July we enjoy the visual warmth of red and pink roses, red hot pokers and bright red poppies.
A carpet of bluebells occurs in April and May each year.
In the living world most organisms contain colour, and colours are produced by different groups of pigments. The pigments found in plants and flowers are known as biological pigments, which are composed of cells and molecules. Similarly to chlorophyll, they absorb some wavelengths of light but reflect others. We can categorize these pigments into groups, most commonly anthocyanins, carotenoids, flavonoids and betalains.
Anthocyanins
Anthocyanins are responsible for providing red through to blue pigments in many species and may occur in several parts of a plant, including the fruits, roots and stems as well as flowers and leaves. Many dark fruits such as blackberries, blueberries and blackcurrants contain high levels of anthocyanins. These pigments are sensitive to the pH variables in soil. For example, some hydrangea species develop blue pigmentation in acidic soils, but pink pigmentation when the pH level rises in alkaline soils (white hydrangea species are unaffected by soil pH). Anthocyanin pigments become very prominent during autumn, when the leaves of deciduous trees change colour and the green-dominant chlorophyll pigment begins to break down.
High levels of anthocyanin pigments are found in blackberries.
In hydrangea, anthocyanin pigments are sensitive to pH variables in soils, becoming dominantly blue in acidic soil and dominantly pink in alkaline soil.
CHLOROPHYLL AND THE PROCESS OF PHOTOSYNTHESIS
Chlorophyll is involved with the process of photosynthesis in organisms such as green plants and green algae. The green chlorophyll pigments are produced when the absorption of light energy, water and carbon dioxide is converted into chemical energy (the photosynthesis process) and the energy is then subsequently used to synthesize the carbohydrates that nourish a plant. Oxygen (O2) is the by-product of the photosynthesis process. Leaves appear green due to their content of chlorophyll pigment, but eventually the chlorophyll becomes unsustainable towards the end of the summer and during autumn, when the sun produces less light and the days become shorter and shorter. At this stage, the chlorophyll diminishes completely. This is when we see leaves begin to change to their beautiful autumn hues of yellows, golds, ochres and reds.
Chlorophyll eventually breaks down to reveal beautiful yellows, golds and reds.
The chlorophyll pigment in the leaves of deciduous trees breaks down before the leaves fall completely at the end of autumn.
In Rhus trichocarpa the onset of colour change is a gradual process on each leaflet.
Carotenoids
Carotenoids provide red, orange and yellow pigments and are typically found in fruits, vegetables and fungi. Species such as tomatoes, carrots, pumpkins and grapefruit contain carotenoid pigments.
Carotenoids are typically found in fruits and vegetables.
The Yellow Shelf Fungus (Laetiporus sulphureus) contains carotenoid pigments.
Species of Boletus, Amanita and Sarcoscypha fungi are predominantly red pigmented.
Lactarius semisanguifluss. (Leigh Ann Gale)
Flavonoids
Flavonoids are responsible for the yellow pigments typically found in berries and citrus fruits, but are also found in other food plants such as strawberries, cabbage, cinnamon and walnuts.
Edible foods such as strawberries, cabbage and citrus fruit are rich in flavonoid pigments.
Betalains
Betalain pigments replace anthocyanins in some flowers and fruits. They provide violet, red, orange and yellow colouration and are typically found in species such as bougainvillea, carnations and beetroots. Betalains are divided into two types: one of red/violet (betacyanins), the other of yellow/orange (betaxanthins). Betalain pigments are believed to possibly have fungicidal properties.
The brightly coloured flowers of bouganvillea are produced from betalain pigments.
The deep-red colouration of beetroot is produced by betalain pigments.
UNCOMMON FLOWER COLOURS
Flower colours such as yellows, oranges, reds and pinks are often thought of as the colours we see most in the plant kingdom. However, if we consider what we might term as ‘uncommon’ colours, we might think of black, brown, blue and even green. The various pigments and pigment types that determine the colouration of flowers are set within the gene pool for each plant, and this is largely accounted for because plants evolved alongside their pollinators. For example, an abundance of short-wavelength, brightly coloured flowers (yellow, blue and violet), which honeybees are attracted to, have evolved because of the bees’ ability to see these certain colours in addition to shorter ultraviolet wavelengths of colour, which humans are unable to see. Honeybees are unable to see the longest wavelength colour, red.
A summary of plant kingdom pigments and their colours
Pigment
Colouration
Found in
Chlorophyll
Green
Green plants and algae
Anthocyanins
Red, purple, blue
Dark fruits, hydrangea
Carotenoids
Pink, red, orange and yellow
Some plants plus vegetables such as carrots and pumpkins
Flavonoids
Purple, blue, red and yellow
Berries, citrus fruits and aubergines
Betalains
Violet, red, orange and yellow
Some flowers and fungi
Blue flowers
Although there are a good number of blue-flowering plants, e.g. cornflowers, agapanthus and bluebells, compared with the abundance of the more common colours of yellow, orange, red and pink there are relatively few. Many flowers are coloured by the anthocyanin group of pigments and blue flowers are also pigmented by this group, but it is the alteration in the chemical make-up of the anthocyanins that is responsible for specific blue colouration. Some of these pigment alterations are derived from pigment modifications. For example, in plumbago the dominant delphinidin-named pigment (found abundantly in delphinium) is modified somewhat to increase its absorbance of longer light wavelengths.
In plumbago the delphinidin pigment is modified to increase its absorbance of longer light wavelengths.
The South African perennial agapanthus is a popular cultivar available in a variety of blue colours.
Jade Vine (Strongylodon macrobotrys) flowers are believed to possibly contain a modified anthocyanin pigment.
Other factors influencing blue pigmentation in blue flowers derive from chemical alterations, as already identified in the example of hydrangea. When aluminium is removed from the chemical compound, pink hues of hydrangea flowers are the result, because a lack of aluminium causes a higher alkaline content in the soil.
Green flowers
It is not surprising that we seldom see green flowers, given that they would blend in with their surrounding foliage too much, making them difficult for pollinators to see. However, a minority of green flowers do exist, though their methods of pollination may be different. For example, they may be self-pollinating in the case of very small flowers, or wind-pollinated in the case of grasses.
Green-coloured orchid cultivars are growing in popularity.
The exotic Jade Vine (Strongylodon macrobotrys) with its blue/green flowers does not contain chlorophyll, but an as-yet unidentified pigment thought possibly to be a modified anthocyanin.
There is growing interest in the cultivation of green orchids, such as species of Cymbidium, Dendrobium and Phalaenopsis orchids.
Brown pigments in flowers
We are most familiar with brown pigments existing in twigs and branches, tree bark, and decaying autumn leaf matter. However, there is a small number of flowering plants and shrubs, especially those that grow in the wild, which contain brown pigments. These include, for example, the common bulrush, which displays its summer spike of female flowers; the late-summer flowering Clematis ‘Vince Denny’, and some members of the plantain (Plantago) family such as Ribwort Plantain (Plantago lanceolata) and Greater Plantain (Plantago major), which produce fairly small, insignificant brown flowers.
The common bulrush displays a spike of brown, female flowers.
The unusual brown flowers of Clematis ‘Vince Denny’ are produced from midsummer to early autumn.
The small brown flowers of Ribwort Plantain (Plantago lanceolata) can be seen in grassy fields during the summer.
Efforts have been made by plant breeders to cultivate less common brown-flowering species as garden flowers over the centuries. Brown is perceived as an unusual colour in gardens, but many favourites nowadays, such as cosmos, iris and gladioli, have brown varieties readily available to plant in our borders.
Because colour is very subjective, ‘brown’ may be perceived slightly differently by different people. However, some brown species are aptly named, associated as they are with objects or substances that we typically consider brown-coloured. ‘Chocolate’ is a good example: Dahlia ‘Chocolate Sundae’, Calla lily ‘Hot Chocolate’ (Zantedeschia Hybrid), and ‘Chocolate Sunflower’ (Helianthus annuus ‘Chocolate’). Other brown-flowering species with evocative names include a variety of aquilegia called ‘Roman Bronze’, a hibiscus variety known as ‘Crème de Cacao’ and a bearded iris variety known as ‘Bronzette Star’.
We often associate brown in nature as a colour representing fading or degradation, especially in dying blooms and the breaking down of the pigments in autumn foliage. Compost is a brown/black colour, and the fallen leaves of deciduous trees produce a brown carpet on the forest floor until it clears, and fresh, new green growth appears again in spring.
The brown flowers of Cosmos astrosanguineus ‘Chocamocha’ are delicately scented with chocolate.
As colourful flowers fade, they take on muted tones, especially brown hues.
We associate the colour brown with the ripening of crops and harvest time.
The outer shells of acorns and horse chestnuts, when brown, signify the ripe fruits inside.
Faded blooms, such as those of roses, hydrangea and chrysanthemums, all turn shades of warm and cool browns, some often retaining muted tones of their original pigments as well, and we associate this with the natural process in the lifecycle of plants. In a similar way, when we see fields of crops at harvest time, we associate the brown-coloured cereals as being ripe and ready for harvesting; and the fruits of deciduous trees such as acorns, beech nuts and horse chestnuts, all contained in their brown cases, indicate the ripe fruits inside them.
Metallic-effect colours of plants
Occasionally we come across plants whose foliage appears metallic. For example, Calocephalus brownii ‘Challenge’ with its striking grey/silver strand-like foliage; Eleagnus pungens with silvery/white leaf undersides compared with the variegated green/yellow top surfaces; and species of Aluminium Plant, well known for patches of metallic silver in the variegated leaves. Other well-known examples grown specifically for their attractive metallic foliage include the Metal-Leaf Begonia (Begonia incarnata), with its metallic gloss covering its heavily lobed leaves, and Eryngium ‘Silver Ghost’, a sea holly living up to its name and bearing very silver grey/blue prickly foliage.
The grey/silver metallic foliage of Calocephalus brownii ‘Challenge’ is particularly striking.
The metallic-looking undersides of Eleagnus pungens leaves create a contrasting effect with the variegated green top surfaces.
Patches of metallic silver are interwoven with the green colouring of Aluminium Plant (Pilea) leaves, producing an almost symmetrical pattern.
How, though, does the foliage appear metallic in these plants? The metallic effect often occurs on foliage that grows naturally in shade. When green foliage is subjected to normal light levels, photosynthesis is possible by chloroplasts within the leaf structure – blue, red and green light is absorbed through them into tiny cells known as plastids. However, in foliage that appears metallic, these tiny cells are modified and are known as iridoplasts. At low light levels, this modification allows the leaves to both absorb and reflect the light at the same time, and this combination produces the effect of very strong colours when viewed from certain angles. The metallic effect is known as iridescence. It is thought that iridescence in the foliage of shade-dwelling plants is therefore helpful, due to the specific reflection of blue light and the slower absorption rate of green light that is needed to maximize photosynthesis.
The wild flower, Variegated Yellow Archangel (Lamiastrum galeobdolon argentatum), exhibits metallic effect patches in its foliage.
Large succulents such as Agave americana produce silvery foliage to protect the plant from very dry or windy weather conditions.
Blackcurrants, coloured ‘black’, comprise many very dark-coloured pigments in nature.
The flowering spike of Aloe yucca produces white flowers that are achromatic.
Metallic-effect foliage is also found in plants that grow in very dry, arid conditions or in coastal regions, where they are subjected to extreme weather conditions such as intense heat or drying winds. The metallic effect is often produced by a system of small hairs on the foliage, designed to protect the foliage from these extreme growing conditions.
Black and white in nature
Scientifically speaking, black is not a colour – it is the absence of colour in the visible spectrum. White, however, is a colour because white light is composed of all the colours of the visible spectrum. It was the mathematician Isaac Newton who demonstrated this, using a prism; when white light is passed through the prism, it changes direction (refraction) to reveal a rainbow.
When considering whether black and white are colours in the natural world, it is necessary to analyse the pigments and molecules within the cells and fibres of an organism. We are familiar with coal, oil and soot, and certain gemstones such as black tourmaline that we classify as being black, and we are satisfied that polar bears, ice and rocks such as chalk and limestone are white. Black and white organisms, however, are achromatic, meaning that they lack pigmentation to give them any colour. This is easier to conceptualize in the case of white subject matter, but black organisms cannot truly be achromatic. Instead, they consist of many combined pigments such as dark reds, blues and purples, which collectively give the illusion of being dense black. Additionally, white organisms because of their lightness reflect light, and black organisms because of their colour density absorb light, making the contrast between white and black even greater.
These considerations of black and white in nature may seem confusing, but they are important factors for the botanical artist. It is always a good idea to mix your own blacks by using the deep colours in your watercolour palette; as for white subject matter, despite being achromatic you will still need very small quantities of pigment to convey form, structure and texture. You will not have a requirement for premixed black in a set of watercolours, such as Lamp Black or Mars Black, and only limited need for a pure white watercolour such as Chinese White or Titanium White (seeChapter 4).
‘Black’ plants, flowers and foliage
In nature pure black is not a natural colour. We do often see plants, however – foliage and flowers – which are ‘black’; but as we have learned, these are very dark colours that when combined give the illusion of being black. ‘Black’ petals contain pigmentation that absorbs certain light wavelengths, while other wavelengths of light are reflected to the eye. For years, horticulturalists have attempted to breed pure black flowers such as black dahlias, petunias and pansies, but they are never truly a pure, neutral black but instead very dark purples, blues and reds. Many ‘black’ plants have been named to include the word black in their name, or include words that pertain to darkness, night time etc. For example, Petunia ‘Back to Black’, Zantedeschia Calla Lily ‘Black Star’, and Tulipa ‘Queen of the Night’.
Many ‘black’-coloured plants are aptly named, such as Petunia ‘Back to Black’.
Heuchera ‘Black Tafetta’ produces black foliage with a slight redpurplish tone.
The younger leaves of Ophiopognon planiscapus ‘Nigrescens’ darken to a cool black colour as they mature.
The deep-cut purple-black foliage of Acer Sambucus nigra ‘Black Lace’ makes a perfect backdrop to lighter coloured plants, or a dramatic standalone specimen.
A number of black-foliage plants have also been bred over the years, such as Heuchera ‘Black Taffeta’, Ophiopognon planiscapus ‘Nigrescens’ and Colocasia ‘Black Magic’.
To obtain ‘black’-flowering and -foliage plants, breeders need to cross-pollinate plants that contain high levels of both red and blue anthocyanin pigments. Together, these selections produce the darkest of purples and very deep reds and are the nearest to pure, neutral black that can possibly be made.
White flowers
It is true that ‘white’ flowers are more common than ‘black’ ones, and we generally class ‘white’ flowers to include ivory and cream blooms as well, until too much yellow pigment becomes visible and then we might label them as pale yellow.
Most flowers are coloured to attract pollinators and many that are attractive to bees and butterflies bloom during daylight hours when these pollinators are active. However, some plants have evolved to open their flowers at dusk or even during the night when their pollinators, such as moths and bats, are nocturnally active. For these night-flowering plants, coloured flowers are of little benefit as nocturnal pollinators are attracted to light; white flowers tend to reflect moonlight and are therefore far more visible in low light levels. White flowers also often have strong, pungent scents, which is an additional asset to attract pollinators.
Some flowers such as honeysuckle are strongly scented in the evenings to attract pollinators such as moths.
Species of Spirea are pollinated by several different winged pollinators.
White-flowering Camellia species open their flowers during daylight, attracting winged insect pollinators.
