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ОглавлениеCHAPTER TWO
Developing knowledge of plants: an introduction to plant science
Introduction
For many embarking on a study of herbal medicine, it is the plants themselves that are so attractive and interesting. Their extraordinary diversity and beauty combined with their manifold usefulness pro-vokes wonder and fascination. Plants have formed a major role as food, as medicine and as comfort at key stages of our lives since the earliest humans walked this Earth; plant medicines are also used by other-than-human species including other primates. Many cultural applications of plants are so embedded as to form part of language and ritual, even in the most modern of societies.
This chapter explores some fundamentals of plants as living organisms, in the same way that we look at human anatomy and physiology. Building our knowledge in the accurate identification and classification of plants and their families helps create a sound basis for expanding this learning. Using this information to sensorially deepen your knowledge of plants will continue your study and learning well beyond this introduction, and the scope of this book. In three of the following chapters of this book we will look in more depth at 15 key medicinal plants used in Western herbal medicine. We can all read and research in great detail about each of these magnificent healing herbs. We would invite you, however, to first consider them as the living beings that they are, and to explore your own interaction with them.
Tea tasting Exercise: Mary and Anita independently taste fennel seed. Drawing of ‘how it feels’.
In this chapter we will teach you a simple tasting technique to introduce the concept of using our senses to gain information about plants. You can then compare this to what others have written about those medicinal plants and their effects.
We begin however, by looking closely at four key medicinal plant families. We will explore similarities within those families, whether in terms of structure, or in terms of compounds and medicinal uses, and we will introduce some of the compounds created by plants that are of particular use to the herbalist.
The scientific naming of plants
Plant families included in this chapter include the rose family, the carrot or parsley family, the mint or deadnettle family and the sunflower or daisy family. In botanical science, plants are given scientific names, and are grouped then into scientific families.
Each scientific family name ends in ‘aceae’:
Carrot family: Apiaceae
Mint family: Lamiaceae
Sunflower or daisy family: Asteraceae
Rose family: Rosaceae
All these four families are dicotyledonous plants (see definition below), and many will be familiar to you. For example, in the Rosaceae we have apple, pear, cherry, apricot, almond, as well as roses of all types. Of the two main divisions of plants—dicotyledons and monocotyledons, the dicots form by far the largest group.
Definition—Dicotyledons: Dicotyledons are plants that grow from the embryo within the seed with a pair of first leaves, or seed leaves, known as cotyledons.
Alliums or members of the onion and garlic family are monocotyledons having a single seed leaf. Other well-known monocotyledenous plants include ginger (Zingiber officinale Roscoe.), and turmeric (Curcuma longa L.).
These families can be further divided into tribes and sub-tribes, and eventually into genera (singular = genus). The genus is important because it is the first name of the two scientific Latin names given to individual plants. The second name refers to the species of that plant genus. Whenever we refer to the scientific name of a plant, we will use the genus name followed by the species name.
So let's take thyme as an example. You may know that there are many different types of thyme, such as common or garden thyme (Thymus vulgaris L.), and wild creeping thyme (Thymus serpyllum L.).
Each one is in the genus Thymus, in the mint family (Lamiaceae family), and we can be sure which thyme we are talking about by adding the name of the species of thyme to the genus name to create the scientific name e.g., vulgaris.
Thus, as you can see from these examples, using the scientific name avoids confusion:
Alchemilla vulgaris aggr. auct. = Lady's mantle
Alchemilla arvensis (L.) Scop. = parsley piert
Petroselinum crispum (Mill.) Fuss = garden parsley
This format of genus + species is called binomial nomenclature, and was first developed into formal taxonomy by Carl Linnaeus. Note that the genus name carries a capital letter, the species name does not, and both are usually written in italics. Humans, for example, are classified as Homo sapiens, European green woodpeckers are Picus viridis. The name of the particular variety of the species can also be added after the species name to make the classification even more exact (e.g., Thymus vulgaris Argenteus (silver thyme)). Note that the variety is not written in italics. You can also see, at the end of the latin names the initial of the botanist who named that plant. For example Curcuma longa L. where the L stands for Linnaeus. Another custom to note relates to how the latin name changes over time. If a plant is renamed, the initials of the botanist who originally named the plant are then put in brackets and the initials of the botanist who supplied the new name are put after this. You can see an example of this on the previous page where Petroselenium crispum (Mill.) Fuss. was originally named by the botanist Philip Miller, and later renamed by Johann Fuss.
Common thyme (Thymus vulgaris L.)
Creeping thyme (Thymus serpyllum L.)
Common names and scientific names
It can seem intimidating to learn the scientific name for each plant. Common names often seem easier to remember than scientific names, but they are not as precise and do not reflect modern scientific taxonomy.
Not only can a common name refer to many different plants, but a single species can have more than one common name; there may be lots of common names for the same plant! This can lead to confusion, and potentially to serious problems if people confuse poisonous species or varieties with harmless ones. The scientific name is truly international and so also forms a shared language across the world.
Here in the UK, a record of local names for the same plant was recorded by Geoffrey Grigson in his book An Englishman's Flora first published in 1975 by Paladin Books. His list of names used for St John's wort, Hypericum perforatum L. include:
| Amber | Balm of the warrior's wound |
| Cammock | St John's wort |
| Penny John | Rosin rose |
| Touch-and-heal |
The names often hint at earlier uses.1
Common and botanical names are often interesting as a record of social history and may also contain information about the plant itself.
St. John's wort (Hypericum perforatum L.)
Shrubby St. John's Wort (Hypericum androsaemum L.)
Hypericum perforatum L., and a related plant Hypericum androsaemum L. were both sometimes referred to as ‘Amber’. This name was supposedly because of the dried leaves when crushed smelled like ambergris. One explanation of the name Hypericum is from a corruption of the name ‘park’ by which this plant was known to ancient herbalists. Before scientific nomenclature had properly catalogued Hypericum androsaemum L. it was incorrectly thought to be the agnus-castus described by Pliny (Vitex agnus-castus L.). This is an example from antiquity of why stan-dardising names for plants is very important and helpful.
Definition—Authority citation: In scientific botanical nomenclature, an author citation refers to the person or group of people who first published the scientific name of a plant as specified by the international code of nomenclature. Standardisation of author names has been achieved for almost all plants, so that for example, a plant classified by Carl Linnaeus (1707–1778), is now cited as L. So—Alchemilla vulgaris L. refers to Lady's mantle, as classified by Linnaeus.
Scientific names can give you important information about a plant.
Marigold (Calendula officinalis L.)
Mugwort (Artemisia vulgaris L.)
For example, the use of the variety name ‘officinalis’, meaning ‘of the office’, tells us that it was once an officially recognised medicinal plant. An example is marigold, Calendula officinalis L.
Also, the use of the variety name, as in ‘vulgaris’, meaning ‘used commonly by people’, signifies the traditional use in folk traditions as a medicinal plant. An example is mugwort, Artemisia vulgaris L.
Four important medicinal plant families
One of the (many) magnificent things about herbal medicine is that you can meet the agents of healing, the plants themselves, in their natural environment. You can interact closely with plants on many levels, including being out in nature, and observing the changes with the seasons. It is interesting to reflect on what happens through the cycle of the year, noticing the changes all living beings need to make in summer heat or winter cold.
Members of particular plant families are often recognisable by similarities of form, for example similarities between their flowers, stems, seeds and fruits. We now look in more detail at the Apiaceae, Lamiaceae, Asteraceae and Rosaceae plant families as used in herbal medicine. What features do plants share within the same family, and are there compounds and medicinal actions that are shared too?
It is great to learn about wonderful plants growing near where you live. Perhaps you have a plant from one of these families you can get to know more, over the coming year? Correct plant identification is the place to start, and is essential if you intend to use a herb collected from the wild, or even from your garden. Using a plant identification guide-book is complicated at first but becomes easier with practice. Identification of plants is often easiest when the plant is flowering and sometimes impossible when it is not. Learning a new plant in your locality, and revisiting it throughout the year will help you notice it in other locations and commit it to memory. Buying species-correct plants from a nursery, and then growing them in your garden is another way to really get to know a plant in more depth. You may then notice all sorts of features that are not necessarily recorded in popular plant manuals.
Using a hand lens, smelling, tasting, feeling, growing and harvesting plants are all ways we can use our senses to enrich our plant knowledge through observation, just as we use observation techniques in the practice of herbal medicine.2
Foraging guidelines
When foraging or out trying to identify a plant for edible/medicinal purposes, it is very important that you are absolutely certain you have identified it correctly before tasting it, and sometimes even before picking it, as some plants have an irritant sap.
•Mid-spring is a good time of year to start identification.
•If in doubt, ask someone, and never eat anything about which you are not 100% certain.
•Always ask permission of the landowner before picking. Take care not to trespass.
•Check you are not picking a rare protected plant species.
•Avoid contaminated sites (industrial, commercial, canine) where possible.
•Do not over-pick nor take all of a plant from one site.
•Only harvest from abundant populations.
•Leave plenty for other wild creatures.
•Do not take more than you need.
•Avoid or minimise damage to habitat—do not trample!
•Remember the Countryside Code.
Some checks to ensure correct identification:
Location does the plant grow in the location specified in your wild-flower guide?
Time of year is this plant flowering at the expected time of year? If not, it may be something else.
Height does your plant fit within the height range given?
Stems stems can rise from the base of the plant or branch out from a main stem. Stems can be rough or smooth, ridged, hollow, coloured or hairy.
Leaves take your time to really observe. Leaves are remarkably variable even on one plant. Look for leaf shape, leaf margin, leaf veining, the upper surface and underneath of the leaf, and whether the leaf is smooth (glabrous) or hairy (hirsute).
Petals or sepals check for shape, number, the colour of petals and sepals.
Flowers check not just colour, but flowering time and shape. Stamens and stigma are the male and female reproductive organs, and also usually occur in a specific number, and arrangement.
Seed how does your plant manage seed dispersal? Use a hand lens to see the seed more clearly.
Definitions—Petals (a) are modified leaves that surround the reproductive parts of flowers. They are often brightly coloured or unusually shaped to attract pollinators. They are usually accompanied by another set of specialized leaves called sepals (b). The group of petals in one flower are collectively called the corolla (c), a group of sepals collectively form a calyx (d).
Carrot family (Apiaceae)
(Known as the carrot, celery or cow parsley family).
This family consists of plants that can be annual, biennial or perennial.
Definition—Annual, perennial, biennial: Annuals germinate, blossom, produce seed and die in one growing season. Perennials flower reliably every year. Their leaves may die back, but the roots do not, the plant re-emerges from this root. Biennials take 2 years to complete their biological lifecycle. They develop their leaves (often in a rosette), stem (often very short) and roots in the first year, then produce flowers and seed in the second. In doing so, they usually use up their root storage and die. This is particularly important for medicinal plant harvesting of biennials, like Angelica archangelica L. The roots will ideally be harvested at the end of the first year, and before the start of the growth in the second.
A central characteristic of this family is that their flowers can often be grouped in broad or tight heads known as umbels. All the flowers are borne on stalks arising from one point on the main stem, a), rather like the spokes of an umbrella. Each main spoke can be further divided into secondary umbels b).
The mass of numerous small flowers held closely together in broad, flat or rounded heads is ideal for insects to land on, thus promoting pollination.
The leaves of members of this family are alternate. Alternate leaves occur when leaves are arranged singly, in an ascending spiral arrangement along a branch or stem.
Leaves are large and generally pinnately divided (feather like), often with inflated and sheathing leaf bases.
Flowers of the Apiaceae are generally made up of five sepals and five petals separate, usually notched with an incurve.3
This family can be difficult to correctly identify out in the field. Be very careful to avoid picking (due to skin reactions), or ingesting (due to poisonous compounds) certain members of this family such as giant hogweed Heracleum mantegazzianum Sommier & Levier., hemlock water dropwort Oenanthe crocata L. or fool's parsley Aethusa cynapium L.
Definition—Pinnate: feather-like. Pinnate leaves of yarrow or elder show different types of pinnate leaf forms.
Despite these more poisonous family members, this family also contains some of the most fantastic, useful and important medicinal plants for herbalists including:
•Celery, Apium graveolens L.
•Chervil, Anthriscus cerefolium Hoffm.
•Sweet cicely, Myrrhis odorata (L.) Scop
•Alexanders, Smyrnium olusatrum L.
•Aniseed, Pimpinella anisum L.
•Fennel, Foeniculum vulgare Mill.
•Dill, Anethum graveolens L.
•Garden parsley, Petroselinium crispum (Mill.) Nyman.
•Caraway, Carum carvi L.
•Coriander, Coriandrum sativum L.
•Lovage, Ligusticum levisticum L.
•Garden angelica, Angelica archangelica L.
•Wild angelica, Angelica sylvestris L.
Plant compounds of this family, other than aromatic volatile oils and resins, include coumarins (e.g., umbelliferone), furo-coumarins, chromono-coumarins, terpenes and sesquiterpenes, triterpenoid saponins and acetylenic compounds. Alkaloids occur rarely in Apiaceae plants, although hemlock Conium maculatum L. contains the alkaloid coniine.4
We examine the important plant constituents called saponins, later in this chapter.
Mint family (Lamiaceae)
(Known as the mint or deadnettle family).
White deadnettle (Lamium album L.)
Catnip (Nepeta cataria L.)
This family is made up of herbs or shrubs, generally with square stems, often with glandular and aromatic trichomes (hair-like projections) on their surfaces. It includes plants such as mints, thymes and woundworts, all of which have a recognisable scent.5
Leaves are opposite, and usually simple. Opposite leaves occur when two leaves grow at the same position on the stem on opposite sides. Often the next pair of leaves will grow higher up the stem at right angles to the pair below, and so on up the stem towards the flower clusters.
The flowers of plants in this family are referred to as irregular or zygomorphic and are found on the stem in distinct lateral clusters or verticillasters. These often whorl around the stem, making a leafy spike known as a panicle.
If you look at white dead nettle, Lamium album L. flowers or catnip, Nepeta cataria L. you will recognise the distinct shape of the flowers of this family.
Definition—Zygomorphic: Botanical adjective (of a flower) having only one plane of symmetry, as in a pea or snapdragon. Bilaterally symmetrical.
In botanical classification, flowers of the Lamiaceae family are described thus:
The calyx has five teeth, sometimes two-lipped. The corolla is two-lipped with a couple of exceptions, and the lower lip is three-lobed, the upper lip is two-lobed.3
This botanical ‘shorthand’ conveys a lot of information and can be difficult to follow at first. We can use books on wildflowers to help us identify plants, both by using the pictures and this botanical shorthand. It gets easier with practice.
There are over 3000 species of Lamiaceae worldwide, including many familiar aromatic medicinal herbs such as:
•Lemon balm, Melissa officinalis L.
•Basil, Ocimum basilicum L.
•Thyme, Thymus vulgaris L.
•Rosemary, Rosmarinus officinalis L.
•Lavender, Lavandula officinalis L.
•Motherwort, Leonurus cardiaca L.
•Sage, Salvia officinalis L.
•White horehound, Marrubium vulgare L.
•Catnip, Nepeta cataria L.
Many of the species of the Lamiaceae are used as ornamentals, garden and culinary herbs as well as medicinal or aromatic herbs in cosmetics, foods, hygiene products and perfumery. The secondary metabolites made by this family include terpenoids and flavonoids, although alkaloids, iridoids and ursolic acid have been found. Many of the medicinal uses are assumed to be connected to the terpenic constituents of the essential oils of these plants, which are fungicidal, antispasmodic and prebiotic.6
Definition—Secondary metabolites: Secondary metabolites are specialised organic compounds produced by plants that are not required for normal growth, photosynthesis, development or reproduction. They are made and broken down in response to environmental factors, and may be essential for protection from insect or microbial attack for example.
It is these secondary compounds that are of particular use to the herbal medicine user over and above the proteins and carbohydrates, vitamins and minerals made by plants that we might use for food.
A discussion of the properties of essential oils will be made later in this chapter.
Daisy family (Asteraceae)
(Known as the daisy or sunflower family).
The daisy, like the sunflower, is easily recognisable; but what appears to be the flower of the daisy is in fact an inflorescence—a head of many, many tiny flowers or tubular florets, grouped together in a head or capitulum, often with lingulate (strap-shaped) ray florets looking like petals around the outer edge.
In the case of common daisy, Bellis perennis L., this arrangement gives the appearance of white petals around a yellow centre, but what we are actually seeing is white strap-like ray florets a), arranged around like rays of the sun, around a capitulum or head, of many tiny individual yellow flowers, b).
This head, known as a disc floret, may be flattened or domed. The disc florets of the sunflower, Helianthus annuus L. can appear quite flattened, whereas the daisy is often more domed.
If you have a small hand lens with 5X or 10X magnification, it is fascinating to look at plants in the daisy family and see in magnification all the tiny flowers that make up the head or capitulum.
Interesting Fact: Daisies
The name ‘daisy’ is from the words ‘days-eye’, meaning the flowers move on their stems and follow the sun rising in the East and setting in the West.
Members of the daisy family have either all strap or ligulate florets, like a dandelion, Taraxacum officinale F.H.Wigg. or they have all tubular florets, like common tansy, Tanacetum vulgare L.
Moreover, not all members of the Asteraceae have florets sitting on a flat capitulum like a daisy. One such example is the wonderful wild mugwort, Artemisia vulgaris L., and another is the equally charismatic, wild yarrow, Achillea millefolium L.
The Echinacea species belong to the Asteraceae family, and demonstrate firm florets in the centre of the capitulum, giving rise to their name meaning ‘like a hedgehog’, from the Greek ‘Ekhinos’.
Other important medicinal plants found within the Asteraceae family include:
•Burdock, Arctium lappa L.
•Milk thistle, Silybum marianum (L.) Gaertn
•Goldenrod, Solidago virguarea L.
•Elecampane, Inula helenium L.
•German chamomile, Matricaria chamomilla (L.) Rauschert
•Pot marigold, Calendula officinalis L.
•Feverfew, Tanacetum parthenium (L.) Sch.Bip
•Arnica, Arnica montana L.
•Roman chamomile, Anthemis nobilis L.
•Boneset, Eupatorium perfoliatum L.
•Wormwood, Artemisia absinthium L.
•Gumweed, Grindelia camporum Greene
•Coltsfoot, Tussilago farfara L.
•Tansy, Tanacetum vulgare L.
Ethnopharmacological studies have identified the Asteraceae family of plants as containing some members with notable healing properties.7 Our common daisy (Bellis perennis L.) has a long history of use in the treatment of wounds and bruises. Marigold (Calendula officinalis L.) is also a supreme healer from this family, and we will be looking at this more closely in Chapter 6.
Many Asteraceae members feature as food plants (sunflower Helianthus annus L. and artichoke, Cynara cardunculus L.), and they have many useful medicinal compounds including lipids, flavonoids, terpenoids, alkaloids, sesquiterpene lactones, essential oils and mucilages.4
We shall take a more in-depth look at the wonderful world of mucilages later in this chapter.
Rose family (Rosaceae)
(Known universally as the rose family).
A diverse family of trees, shrubs and herbs, this family includes well-known fruit-bearing plants such as apples, pears, almonds, peaches, apricots, strawberries, raspberries, cherries and sloes.
Their leaves are alternate, with either simple or compound leaf shapes.
The flowers are terminal and solitary, or appear in racemes, cymes or panicles.
Definition—Raceme, cyme and panicle: These are all botanical words to describe variations in the structure of flower heads.
The flowers are usually composed of five sepals and five petals, but with numerous stamens.
The seeds can be few or many, and are highly variable—as are the fruits, which can vary from a collection of achenes as in meadowsweet, a drupe as in plum and cherry, druplets as in raspberry and blackberry or a pome in apples and pears.
Definition—Drupe, drupelets and pomes: These are all botanical words to describe variations in the structure of seeds.
Some of the wonderful medicinal plants in the Rosaceae family:
•Dog rose, Rosa canina L.
•Agrimony, Agrimonia eupatoria L.
•Meadowsweet, Filipendula ulmaria (L.) Maxim.
•Tormentil, Potentilla erecta (L.) Raeusch
•Raspberry, Rubus ideaus L.
•Blackberry, Rubus fructicosus L.
•Parsley piert, Alchemilla arvensis (L.) Scop. Note: see how common names can be confusing—this is not a parsley!
•Lady's mantle, Alchemilla vulgaris L.
•Hawthorn, Crataegus monogyna Jacq.
Rosaceae family plants contain a large number of useful medicinal compounds such as phenolic acids and polysaccharide compounds, flavonoid glycosides, procyanidins, xanthines, therapeutic tannins, as well as useful minerals and pectins.5
Bramley apple blossom (Malus domestica L.)
Agrimony (Agrimonia eupatoria L.)
Spiral shape of meadowsweet seeds.
In the next section, we look at the plant compounds, the tannins, in more detail.
Plant constituents
In this section, we consider the chemical compounds found in plants in more detail, and review four plant constituents of particular relevance to herbal medicine—mucilages, tannins, saponins and essential oils.
Herbal medicine (phytotherapy) uses whole plants with their array of medicinal compounds, acknowledging synergy between them. Herbal medicine operates in that interesting greeny-grey area somewhere between food and drugs. This is not to be confused with homoeopathy, a completely different system and philosophy, that uses minute dilutions and vibrations of minerals, plants and animal extracts.
Many of the major dietary compounds found in plants beyond basic proteins, carbohydrates and fats, are classed as vitamins and minerals. Examples include the vitamin C found in berries and fruits of the Rosaceae, such as rosehip (Rosa canina L. fructus) or Blackcur-rant (Ribes nigrum L. fructus). It is increasingly understood that many edible plants and herbs contain different types of antioxidant compounds (including vitamin C), and contribute to preventing cell damage around the body.8
The red and blue pigments synthesised by plants into red-blue coloured fruits and vegetables is a signature for the presence of anthocyanins, a secondary metabolite belonging to the class of compounds known as flavonoids. In plants, they may act as an attractor for pollinators or for attracting animals for seed dispersal. In the human body, flavonoids are known to have certain health benefits, rather than providing a direct food source. Flavonoids are mildly astringent, and contribute to the health and integrity of the membranes on the surfaces of our body, for example, in periodontal health and hygiene.9 Flavonoids have also been investigated as one potentially anti-inflammatory constituent of willow bark working in synergy with other compounds. It is now recognised that the anti-inflammatory effects of willow are not entirely the result of salicylates.10
Fibre is another obvious dietary compound that is a potential contributor to health such as the soluble fibre found in linseed, or flax (Linum usitatissimum L.). Soluble fibre has an important prebiotic role as well as contributing to hormone balance and regulation.
Herbal medicine recognises that plant foods can have beneficial well-being outcomes, and many ‘kitchen herbs’ are positively medicinal. For example we can take therapeutic quantities (antibacterial quantities) of raw or powdered garlic (Allium sativum L.).
The herbalist may make recommendations about diet to utilise the helpful benefits of certain foods, but is also focussed on the therapeutic application of plant medicines to restore resilience and function. An assessment of the person's constitution and condition may also result in recommendations of eating certain foods. This is more than just about phytochemicals, in that it is also an ‘energetic’ assessment.11
Choosing a plant for an individual may involve interpretation of numerous beneficial compounds, so that a just a few herbs can formulate a prescription, yet have multiple therapeutic benefits.
The drug (herbal medicine) changes the physis of the body, while on the other hand the food increases its substance.
—Manfred Ullman12
Case history
A woman in her late 60s presented with a long history of digestive discomfort. She had persistent abdominal pain and bloating, with episodes or ‘flare-ups’ of frequent bowel motions—up to 20 per day. Between ‘flare-ups’ her bowel movements were twice daily but felt incomplete, and she had observed a corresponding urinary irritation if her bowels were very upset.
Diagnosed with coeliac disease, she also suspected she was lactose intolerant, and she successfully avoided those foods, whilst eating a balanced diet. She found that eating this way and taking probiotics had helped slightly.
She was motivated to see a medical herbalist after a prolonged ‘flare-up’ of her symptoms following a recent viral infection.
Using plants as a deliberate medicine to restore digestive function was discussed, and a herbal combination was suggested alongside the probiotic capsules and dietary care she had already introduced herself.
Her medicine contained agrimony herb (Agrimonia eupatoria L.), German chamomile flowers (Chamomilla recutita L.), lemon balm herb (Melissa officinalis L.), lavender herb (Lavandula officinalis L.) and Black walnut hull (Juglans nigra L.).
These plants were chosen for a variety of potential effects including antispasmodic, anti-inflammatory, increasing digestive enzymes, prebiotic, antiviral and relaxing and healing (vulnerary). The herbs used are gently warming (often useful for older people), and a balance between drying and moistening was also important.
The patient took a small dose of the combined herbal tincture at each meal to try to improve digestive capacity. She reported that within 24 hours she felt less bloated and thought some of the pains had subsided.
Within a week her bowel movements had regulated to two or three per day but were much more comfortable. After 12 weeks she had had no flare-ups, which had occurred at least monthly prior to starting treatment.
Changing her diet and taking probiotics had helped this lady, but the herbal medicines were specifically selected to address insufficiencies in the function of the gut and gently stimulate them to work.
Although identifying and testing secondary plant metabolites and compounds is a major focus of research, it is important that we should resist any temptation to assume that the action of any plant relies solely on the action of any single chemical or compound. The action of the whole plant is always more than the action of its parts. Synergy is increasingly seen as being a fundamental component of plant medicines in the biological sciences.6
Just as the human body can be broken down into parts in order to study its complexity, medicinal plants can be examined through their compounds, but the plant then needs to be reassembled whole for us to have completeness of understanding.
It is useful to look at plant compounds and constituents nevertheless as they can help to provide:
•Possible explanations for traditional use.
•Possible mechanisms for the medicinal actions of forgotten/un-investigated plants.
•Clarity about possible benefits or negative effects of medicinal plants.
•Illustrate the scope and diversity of plant pharmacology.
Secondary metabolites within a plant form part of an array of constituents, and here we look at four archetypal ones:
•Mucilages
•Tannins
•Saponins
•Essential oils
Mucilages
Mucilages are normal products of metabolism formed within plant cells, and may act as storage material, especially for germinating seeds where they act as a water reservoir.
Mucilages can be found in quantity in the epidermal cells of leaves, as well as inside seeds including psyllium, Plantago ovata Phil. (formerly known as Plantago psyllium and isphagula) and linseed, Linum usitatissimum L. Mucilages are also found in the roots of marshmallow, Althaea officinalis L. and in tree bark, for example slippery elm, Ulmus fulva Michx.13
Though extremely common in plants, gums and mucilages seem to be rather disregarded by pharmacologists. Their action in the human body is largely physical rather than chemical, and they are often capable of reaching the large intestine because they are not completely broken down by the stomach and small intestine in the digestive system. So they can have their demulcent healing effects all of their slippery way down the tubing.
Many well-known herbal medicines that are mucilage-containing have predictable effects on the digestive, respiratory and urinary systems, despite the fact that there will have been no direct contact with the mucilaginous compound beyond the digestive system; that is they do not come into physical contact with the lung or the bladder. This phenomenon raises an important pharmacological question often discussed in plant medicine—how do some medicinal plants manage to affect parts of the body, on a mechanical level, that they physically cannot reach?
It has been acknowledged that some body tissues—such as those found in the respiratory, urinary and digestive systems, share a common embryological root. Even after the embryo has developed and tissues have diversified, they may remain responsive to the same stimuli, and also respond similarly via reflex nerve pathways.11
Actions
Here are some of the potential medicinal actions of mucilages in humans:
•Demulcent (soothing, cooling, anti-inflammatory)
•Emollient (moistening, especially to mucous membranes)
•Nutritive (nourishing, improving tissue integrity)
•Emulsifying (making nutrients available for digestion)
•Prebiotic (encouraging microbiome establishment and diversity)
•Vulnerary (accelerating regeneration of tissues—healing)
•Aiding pharmaco-kinesis (helping with the movement of medicinal constituents into the body).
Traditional Western herbal medicine classifies mucilages as neutral in temperature and moistening. They are considered to be mild and agreeable, even to the most delicate patient. This traditional classification is recognised in addition to more recently discovered pharmacological properties. In Western herbal medicine, there is often a fusion of science with traditional or ‘energetic’ observations. For example, all medicinal herbs can be classified as being either Warm, Neutral or Cool.
Mucilage dripping from a plant.
Medicinal plants containing significant quantities of mucilages include marshmallow, Althaea officinalis L.; comfrey, Symphytum officinale L.; linseed, Linum usitatissimum L.; psyllium seed, Plantago ovata Phil.; and slippery elm, Ulmus fulva Michx.
Mucilages are graded by the ‘swelling index’, that is, by their ability to swell and increase their surface area.13 An alternative word would be gloop!
In the picture above, we can see a perfect example of a mucilage produced from a plant. The Sierra Mixe maize has aerial roots, which produce large quantities of mucilage, which it gives to bacteria for food in return for nitrogen. This is a fine example of ‘gloop’.
Linseed, also known as flax seed, and psyllium seed are often left in water to swell before drinking. The product can then coat and soothe the linings of the digestive system. These herbs tend to taste very mild, and pleasant. It is usually the texture that initially offends some people. However, they are a really great way to explore our sensory interaction with plants!
Tannins
The term ‘tannin’ was first applied to substances present in plants able to combine with the proteins contained in animal hides, preventing their putrefaction and converting them into leather.
Two main groups of tannins are usually recognised—hydrolysable and condensed.
Hydrolysable tannins
If something is hydrolysable, it means it can be broken down by water. Plants that contain large quantities of hydrolysable tannins are not suitable for use internally, nor are they suitable for use on open wounds.
Condensed tannins
Condensed tannins are so named because they are formed from a con-densation of molecules called flavans, related to the flavonoids, a group of compounds highly beneficial to health.8 Unlike hydrolysable tannins, condensed tannins cannot be broken down by water, and tend to form red, insoluble substances and are largely responsible for the brownish colour of so many herbal tinctures! There is little evidence of ill-effects and much evidence of benefit from condensed tannins, so they are considered suitable for both internal use, and for application to open wounds.
One example of a very useful plant in the Rosaceae family is tormentil, Potentilla erecta (L.) Raeusch, which has condensed tannins in its reddish-brown roots. Tormentil was traditionally used to stop diarrhoea, and the positive effects of the tannins it contains are as follows:
•Dries up excessive watery secretions
•Heals digestive membranes
•Increases resilience of membranes against invading infection
•Potentially destroys invading organisms by their ability to precipi-tate proteins
From the beneficial effects of tannins listed above it is easy to see how and why tannins have a strong history of use externally in the treatment of burns. When a tannin solution comes into contact with tissue it interacts with the tissue proteins to form a tough, leathery structure called an eschar. The formation of this eschar acts to seal the wound, thus preventing subsequent infection and allowing new tissue to form. Use of tannins for this purpose was practised during World War I, and was thought to be responsible for saving many lives.
Recent research published in the Malawi Medical Journal in 2005 revisited this technique and concluded that;
This study was not blinded. However, results of this pilot study suggest that the use of tannins may provide benefit by reducing colonisation of Staphylococcus aureus with better quality of healing and at the same time not increasing toxicity.
—L. Chokotho and E. van Hasselt7
(We would like to stress here that any serious burn should be treated by a healthcare professional as a matter of urgency.)
It has been observed that some plants increase their production of tannins in response to grazing by animals. This causes the animals to move on, and not over-graze a particular tree or shrub. Interestingly, the response to produce more tannins also occurs simultaneously in neigh-bouring plants, suggesting that some communication between plants is happening and the plants are helping each other out!
Many tannins have beneficial effects in small to moderate doses by sealing wounds and strengthening mucous membranes. Improvement to the resilience of any epithelial tissue will increase the immunity to infection there.11 Taken in excess, tannins can inhibit nutrient absorption, so that excessive black tea consumption can lead to iron deficiency for this reason.
Interesting Fact: Tea
Incidentally, the plant in the UK we call ‘tea’ is in fact Camellia sinensis L. The word ‘tea’ actually refers to the method of preparation of an infusion or ‘tisane’.
One traditional use of tannin-rich herbs is in mouthwashes to prevent or treat gum disease. Tannin-rich plants were traditionally used as snuff to treat nasal polyps. In barber's shops they were used to stop bleeding from shaving cuts.
You may already be familiar with witch hazel water, prepared from the medicinal plant Hamamelis virginiana L. This distilled water can be applied externally to bruises, helping to seal up the internally broken blood vessels that lead to bleeding under the skin, as in a bruise. Witch hazel water has been a common first aid box ingredient for bruises and sprains. It is prepared from the leaf of the witch hazel tree, and contains hydrolysable tannins that should be used externally only, and on unbroken skin. The bark of witch hazel contains only condensed tannins, and can therefore be used internally.
The sensation we associate with tannins is known as astringent, and the taste is described as Sour. Use of the word Sour with a capital S, suggests an energetic property. Western herbal medicine embraces modern science, but also honours the rational aspects of a more traditional or energetic approach.
Note: Western herbal medicine perspective on ‘sour’ taste. Small amounts of Sour tasting herbs are traditionally considered to increase digestive vigour and tone. They stop the membranes of the body from becoming too flaccid or floppy, and by doing so improve function. They stop ‘leakage’ and loss of vital reserves or nutrients and increase resilience and dynamic strength. These are qualities observed by our forebears that can be explained today in more scientific terms—endothelial resilience.
Saponins
Saponins are glycosides, characterised by their ability to produce frothy foam in water. Their molecular structure allows them to bind to water-soluble (hydrophilic) sugars at one end and fat-soluble (lipophilic) aglycones at the other end.
Taken by mouth, they are relatively harmless, absorbed poorly from the gut following interaction with bacteria in the colon and are regularly consumed in everyday foods. Tomatoes, Solanum lycopersicum L. contain saponins as do many grains.
Note: Plants in the Solanaceae (deadly nightshade) family, such as tomatoes, potatoes, peppers and chilli, contain a distinct sub-group of steroidal saponins known as steroidal-alkaloids that are possibly responsible for lowering plasma cholesterol concentrations.
Medicinal herbs that contain beneficial saponins include sarsaparilla, Smilax ornata Lem., a medicinal herb from the Americas used in non-alcoholic beverages. It was, and still is, used as a therapeutically valuable and safe saponin containing plant.
Saponins have a high molecular weight, and according to their structure are divided into two main groups: steroidal saponins (tetracyclic triterpenoids) and triterpenoid saponins (pentacyclic triterpenoids).
The systemic effects of different saponins include:
•Immunomodulatory, cytotoxic, anti-tumour and anti-mutagenic.
•Anti-inflammatory, anti-allergic, antiviral and antifungal.
•Anti-hepatotoxic and improves nutrient absorption.
•Anti-stress effects, expectorant and adaptogenic effects.
Steroidal saponins
Steroidal saponins are less common in the plant world than other types of saponin, but they are of great pharmacological importance. This is because of their relationship to important compounds in human physiology such as sex hormones, cortisone, diuretic steroids, vitamin D and cardiac glycosides.
Scientific understanding of plant steroidal saponins led to the development and manufacture of drugs such as the contraceptive pill, and a plant that played a crucial role in this development was the edible yam, Dioscorea villosa L., although the plant itself does not contain hormones comparable to the contraceptive pill. Interestingly, wild yam has a long traditional use in the relief of problems associated with sex hormone imbalance.
Plant steroidal saponins have the capacity to block or stimulate receptor sites in our body cells, producing an amphoteric effect.
Definition—Amphoteric: Like a terracotta pot with two handles, it has a capacity to balance in either direction.
Another well-known plant containing steroidal saponins is fenugreek, Trigonella foenum-graecum L. which has a long history of use helping balance blood sugar levels.14 In modern times, it has been shown to have an effect in reducing cholesterol levels and having a positive effect on hormones called androgens.15
Soya beans and ginsengs are other examples of plants containing steroidal saponins.
Triterpenoid (pentacyclic) saponins
This group of saponin compounds can be found in a wide range of dicotyledonous plants including liquorice, Glycyrrhiza glabra L., primrose, Primula veris L., marigold, Calendula officinalis L. and horse chestnut, Aesculus hippocastanum L. The saponins found in these plants have an array of therapeutic benefits, including anti-inflammatory and expectorant effects.
Definition—Expectorant: An expectorant is a compound that makes coughing more effective by promoting the expulsion of mucous/phlegm. Mucous is produced by the body as a natural response to inflammation, in an effort to reduce that inflammation. A build-up of mucous can become a problem in its own right however, especially in the lungs.
Essential oils
Some of the most fascinating and complex of herbal constituents, essential oils (also referred to as volatile oils) are made up of several constituents.
The word volatile comes from the Latin Volare, meaning ‘to fly’, and refers to the fact that the fragrant oil is easily vaporised into the atmo-sphere where we can detect it with our olfactory cells, the smell receptors of our nose.
Poor quality, badly stored, badly prepared or old herbs can lose their essential oils, and thus lose a key component of their potential medicinal effect.
Curiously, essential oils are barely recognised as therapeutic agents by conventional medicine, excepting perhaps peppermint oil.
Mint family
The mint family contains a number of species that contain relatively large amounts of essential oil.
Fresh peppermint, Mentha x piperita L. contains 1% essential oil, and when you make an infusion of healthy peppermint leaves, the array of beneficial compounds in the tea includes essential oil of peppermint.
Note: Colpermin—a medical drug made of peppermint essential (volatile) oil in a capsule—is prescribed for the relief of IBS symptoms.
Using a distillation method, it is possible to isolate an essential oil and extract it from the other compounds found in the leaf. Peppermint pure essential oil is a highly aromatic volatile oil made up of a number of compounds including menthol. Isolated menthol is a highly irritant substance capable of burning the skin.
Definition—Menthol: An organic compound made synthetically or obtained from corn mint, peppermint or other mint oils. It is a waxy, crystalline substance, clear or white in colour, which is solid at room temperature.
The focus by the pharmaceutical industry on individual compounds within plants and their extraction leads to the isolation of substances that are markedly different from, and have different applications to, the original whole plant. They may not even be extracted from a plant at all. Drinking peppermint tea is a different experience from the use of peppermint essential oil in, say, a peppermint sweet, which is different again from using menthol, or mentholated products, which have been manufactured and need to be used with much more care.
Compounds within essential oils
Naturally occurring essential oils are, chemically speaking, mixtures of hydrocarbons and oxygenated compounds including terpenes, monoterpenes and sesquiterpenes. Menthol is an example of a monoterpene, as is camphor. You may recognise these two monoterpenes from common decongestant lozenges and inhalants for blocked nasal passages.
Monoterpenes have antiseptic properties, increase blood flow and act on the nervous system to relax muscles via nerve reflexes. They can therefore help relax painful digestive spasm. They have also been shown to reduce nervous excitability, and there is current research investigating potential beneficial effects of monoterpenes on period pain and childbirth, echoing traditional use of these aromatic compounds in some cultures.16,17
Sensorial tasting of medicinal plants
Our knowledge about plant compounds is nowadays confirmed by technologies not available to our forebears. For ancient peoples it was the sensory clues that gave rise to understanding the usefulness of plants. We still have these highly accurate senses: sight, smell, taste, touch, sound, which can be utilised to help us recognise some of the key qualities that a plant may have.
It is popularly thought that knowledge about the medicinal usefulness of certain plants was gained by trial and error. Whilst to some extent and in certain circumstances this may be true, a number of alternative theories also have credibility.
When asked about how people learned about the medicinal or toxic qualities of the native botanicals, botanist, zoologist and author of the bestselling book Supernature Lyall Watson tells us he was told that they asked the plant, and the plant spoke to them. When pushed for exact details of this, he was told that a leaf or part of the plant was placed on the tongue and information was transmitted.
Although this may sound a rather esoteric explanation of learning, it is an explanation repeated in other traditional cultures around the world. It is a record of some form of communication between human and plant and vice versa.
A young German poet and 17th-century scientist Johann Wolfgang von Goethe explored and systematised a method of plant exploration and ‘communication’ and this method was taken up and recorded by Rudolf Steiner in the early 20th century. He was keen to sensorially experience the phenomenon (in our case a plant), as a whole, not as dissected parts. Their work offers a more qualitative approach to plant study but both authors were keen to emphasise rigour in the application of the process.
For Goethe, it was the use of our senses without the confounding factor of our intellect that would give us an insight into the signature or essence of a living plant being. It allows the phenomenon to be felt by the researcher, perhaps in the same way as an artist captures the essence of a thing, so that we can recognise an oak tree in a painting made of only a few brush strokes.
The contemplation and use of our own ‘scientific instruments’—our senses, can allow profound recognition of inner laws, patterns and relationships that then facilitate the experience of a moment of ‘intu-ition’ and of the wholeness of the phenomenon as itself, or the ‘ur-phenomenon’ as Goethe called it.
Steiner developed this approach into anthroposophical medicine, and other authors and researchers have applied his methodology to plant study—such as Wilhelm Pelikan (Healing Plants I and II). Goethean methodology has also been used in architecture and other areas of life and is promoted by the Goethe Institute in Germany. The science of phenomenology continues to be used in other areas of research.
Goethean methodology was also taken forwards by two pioneering medical herbalists in the 1990s, Keith and Maureen Robertson. Keith and Maureen ran a School of Herbal Medicine in Glasgow, Scotland. They worked with Goethean practitioner Dr Margaret Colquhoun, founder of the Pishwanton Project, and developed the Goethean method for use by students of herbal medicine. They utilised this method to gain insight and deepen relationships with the medicinal plants they were studying and would eventually go on to use in practice.
We would like to acknowledge the source of some of the plant exercises we have included here as being from Keith and Maureen Robertson, medical herbalists, and their fabulous experimental work with Goethean scientist Margaret Colquhoun. Other herbalists have used sensory plant communication and developed techniques similar to this and we wish to acknowledge, Elisabeth Brooke, Hildegarde of Bingen, Juliet de Bairacli-Levi, Stephen Harrod Buhner, Carole Guyette and Christopher Hedley.
Speaking about how physicists strive to discover universal, elementary laws, Einstein once said;
There is no logical path to these laws; only intuition, resting on sympathetic understanding of experience, can reach them. The state of feeling which makes one capable of such achievement is akin to that of the religious worshiper or one who is in love.
—Albert Einstein
A sympathetic understanding of contemplation and experience is at the core of this, and is central to the practice of Goethean methodology.
Here we would like to introduce you to a simple tea tasting exercise involving the leaves of the magnificent nettle plant. This is a sensorial or organoleptic tasting and is used as a key component of plant study in the Heartwood Foundation Course. We reproduce a simplified version of the method here for your use if you wish to conduct your own contemplative sensory plant tastings as we look at more magnificent plants throughout this book. We recommend that you read through the next section thoroughly before embarking on a tea tasting so that you have a good sense of what is needed.
Definition—Organoleptic: acting on, or involving the use of, the sense organs.
Organoleptic tea tasting
We recommend you read through these notes on tea tasting once before you begin.
Preparation
•Make an infusion using 2 tablespoons of fresh nettle leaves, or 1 tablespoon of dried loose-leaf nettle.
•Pour freshly boiling water (approximately 200–300 ml) over the leaves and leave covered for 8–10 minutes.
•Whilst you are waiting, prepare yourself. Be in a comfortable place, with writing and/or drawing materials to hand. Maybe close your eyes for a moment. Take a few slightly deeper breaths. Notice, how you feel. What sounds are around you? Relax. Be present in this moment, right now.
•We would like you to enter into this tasting experience with an open-hearted, innocent, child-like wonder. It is our intention that you enter into this exercise with a sense of humble excitement and anticipation—as if you are meeting a person for the first time. In a way—you are!
Step 1a
•Strain some of the infusion into a clean mug and begin by smelling the tea. Record your observations on the sheet provided.
Notes
You may feel the tea smells ‘fruity’, ‘dry’, ‘moist’, ‘spicy’, ‘mineral-rich’ or ‘lemony’, these are examples of good descriptive words to use. There may be more than just one or two words because of the complexity of compounds within a single plant. It is okay to have only one or two words.
You may also note that smell brings a feeling with it. Observing it is ‘warm’ ‘comforting’ or that it ‘reminds you of something’ are useful observations to make.
It is important not to slip into brain-led value-judgements here. We are using our hearts not our heads. We are enquiring with a completely open mind, and without trying to be clever or to derive a medicinal property. So, try not to say things like ‘I feel this plant may be good for the liver’ as this sort of comment has leapt well beyond observing that you perhaps have an awareness of your abdomen—even just from the smell, or perhaps an awareness of the ears or eyes—just from the smell.
By the way—these notes apply to when you are tasting, as well as when you are smelling, the infusion of the plant. Goethe emphasised that we should try to capture the brief moment as we experience a phenomenon, and immediately before our brains kick in to construct ideas around the experience. He said that our senses are true, our brains and thinking are often not. Also Goethe acknowledged that it is impossible to un-learn everything you know up to this point. So—tasting the infusion of a plant you are already familiar with will inevitably influence you consciously but also unconsciously.
Modern authors who are interested in this technique such as Stephen Buhner, Pamela Montgomery, and others, note that by employing a child-like, but enthusiastic or ‘euphoric’ state we secrete different hormones that affect our ability to allow information past our neural ‘gating’ channels. We induce a hormonal change that allows us to perceive more richly. It is that feeling you get when you are out in nature and filled with a deep sense of joy and harmony and possibly have a flash of insight or inspiration. Trying to feel this way also helps silence the critic in your head who is telling you that you are being silly!
Despite our tendency to allow prior knowledge to influence our senses—it is still worthwhile pursuing this practice. With practice, you will deepen your experience and you will expand your capacity to notice and then verbalise that experience. Maybe you do not feel anything at all at first. Don't try to force it, just keep going, observing, listening. After you have recorded everything you have noticed about the ‘smell’ (approximately 1–3 minutes), it is now time to taste the infusion that you have made.
Step 1b
•Begin by writing down all of the actual taste/tastes that you can. What does it taste like?
•You may at any point in smelling or tasting, experience a sense of colour or movement that is difficult to express in words. Use coloured pencils, pens or crayons to record these colours and movements.
•Re-taste the infusion as you consider the questions below.
Step 2
•As you taste the infusion, where does it go in your body?
•Does it stay in your mouth? Move to your pelvis or evaporate through your skin or none of these!? Suspend disbelief.
Step 3
•How does this plant feel like it moves around your body? Is it slow, sliding and syrupy? Is it tingly and active? Is it strong, fast or gentle in its movement and effect?
Step 4
•What is the infusion doing now you have observed where it is going?
•What is its effect now it is there? Again, be careful not to choose medical words, refrain from using your intellect to describe these active effects. Choose simple descriptive words, try to get right back to the feeling, rather than trying to interpret that feeling.
This tea-testing exercise is only one part of a whole methodology that is beyond the scope of this book to reproduce here.
Keep your tasting (and smelling) notes in a way that you can reference them again at a later date. Make a note of the date and time, the herb tasted and the method used to prepare it. You may taste this plant again and it would be interesting to compare experiences as you do more tastings through your training, and on into practice.
Here are some of our tasting notes from tasting nettle to give you an idea the process.
Nettle tea tasting notes: Example A
What does it smell like?
Slightly chewy. Green. Mild. A hint of citrus but more complex.
What does it taste like?
Warming and drying. Slightly sweet and slightly salty. Tastes like it has a lot of body. Supportive. Cleansing. Softer after 5 minutes. Reminds me of a very thin syrup.
Where is it going?
Pelvis and eyes.
How is it getting there?
Diffusing. Like smoke.
Nettle tea tasting notes: Example B
What does it smell like?
Warm, nutrient, spicy, cooking potatoes, apple-sharp notes, dark, earthy.
What does it taste like?
Soft smooth, pleasant, food-like, mineral, earthy, cooked/boiled vegetables.
Where is it going?
Everywhere! Very slowly works its way everywhere. I am aware of all parts of my physical body that help with balance, my ears, shoulders, hips, hands and feet. Also aware of my skin and my internal organs especially in my mid-back.
How is it getting there?
Still, solid, strong but light (not heavy), calm, balanced.
Note: Nettle. Nettles have adapted their leaves to create hairs known as trichomes that are modified epidermal cells consisting of a bulb filled with formic acid. This is the irritant we all recognise from handling Urtica dioica L.
Nettle leaves in frost.
Nettles need no description, they may be found by feeling, on the darkest night.
—Nicholas Culpeper18
Conclusion
Many herbalists use this sensorial method, or something similar when dispensing their tinctures or making a medicine for a patient. It forms part of our pharmacognosy—the ability to confirm the identity of the commercial product as it arrives, macroscopically, and microscopically. It may be that a dried herb looks a little pale, or brownish on delivery, but using a trusted sense of smell or taste will alert you to any problems with your herbal material, as well as remind you why you love a particular herb.
We hope you have enjoyed this introduction to plants, their anatomy and compounds. Please see the book listed under Further Recommended Reading, which you will find under the Bibliography at the end of this chapter, if you would like to find out more about botany via an easy to use text. We intended to have set the scene for how plants form such a fundamental place as food and also as medicine. The compounds they contain can, and have been, studied independently because medicinal plants have so many identifiable compounds that have profoundly positive activity in human physiology. We also hope to bring you back to the whole. After looking at some of the key components such as tannins, mucilages, oils and saponins, we wish to keep hold of that interconnectedness between us, and nature: how we might trust our experience and our senses to explore and get to know common medicinal plants as wholes. We hope you have enjoyed trying out our tea tasting with one of the plants suggested. May this develop your own capacity to deepen your relationship with yourself and with herbal medicine. The feeling is the medicine!
Bibliography
Abraham, David, The Spell of the Sensuous. Penguin, 1996: Random House.
Brooke, Elisabeth, Women Healers Through History. 1993: The Women's Press.
Buhner, S. H., The Secret Teachings of Plants: In the Direct Perception of Nature. 2004: Bear and Company.
Mills, S., Out of the Earth: The Essential Book of Herbal Medicine. 1991: Penguin Books.
Pelikan, Wilhelm, Healing Plants I and II Insights Through Spiritual Science. 2012: Mercury Press.
Sutton, D., Kingfisher Field Guide to the Wild Flowers of Britain and Northern Europe. 1992: Kingfisher Books (cost effective quick guide).
Streeter, D., C. Hart-Davies, A. Hardcastle and L. Harper, Collins Wild Flower Guide. 2nd ed. 2016: William Collins (ideal for committed naturalists).
Watson, Lyall, Supernature: A Natural History of the Supernatural. 1993: Hodder & Stoughton.
Young, P., The Botany Coloring Book. 1999: Collins Reference.
Further Recommended Reading
Botany in a Day: The patterns method of plant identification. Thomas J. Elpel. 6.1 Edition. Jan 2018. MT, Hops Press.
References
1Grigson, G., The Englishman's Flora. 1975: Paladin Books.
2Colquhoun, M. and A. Ewald, New Eyes For Plants: A Workbook for Observing and Drawing Plants. 2002: Hawthorn Press.
3Blamey, M. and C. Grey-Wilson, Wild Flowers of Britain and Northern Europe. 2003: Cassell.
4Trease, G. E. and W. C. Evans, Pharmacognosy. 14th ed. 1989: WB Saunders Company.
5Barker, J., The Medicinal Flora of Britain and Northwestern Europe. 2001: Winter Press.
6Edwards, S. E. et al., Phytopharmacy: An Evidence-Based Guide to Herbal Medicinal Products. 2015: Wiley Blackwell.
7Chokotho, L. and E. van Hasselt, The use of tannins in the local treatment of burn wounds—a pilot study. Malawi Med J, 2005. 17(1): pp. 19–20.
8Pengelly, A., The Constituents of Medicinal Plants: An Introduction to the Chemistry and Therapeutics of Herbal Medicine. 2nd ed. 2004: CABI Publishing.
9Odongo, C. O. et al., Chewing-stick practices using plants with anti-streptococcal activity in a Ugandan rural community. Front Pharmacol, 2011. 2: p. 13.
10Untergehrer, M. et al., Identification of phase-II metabolites from human serum samples after oral intake of a willow bark extract. Phytomedicine, 2018. 57: pp. 396–402.
11Mills, S., Out Of The Earth: The Essential Book of Herbal Medicine. 1991: Penguin Books.
12Ullman, M., Islamic Medicine. 1997: Edinburgh University Press.
13Evans, W. C., Trease and Evans’ Pharmacognosy. 14th ed. 1999: W. B. Saunders.
14Gaddam, A. et al., Role of Fenugreek in the prevention of type 2 diabetes mellitus in prediabetes. Journal of Diabetes & Metabolic Disorders, 2015. 14(74).
15Rao, A. et al., Testofen, a specialised Trigonella foenum-graecum seed extract reduces age-related symptoms of androgen decrease, increases testosterone levels and improves sexual function in healthy aging males in a double-blind randomised clinical study. Aging Male, 2016. 19(2).
16Fazel, N. et al., Effects of Anethum graveolens L. (Dill) essential oil on the intensity of retained intestinal gas, flatulence and pain after cesarean section: A randomized, double-blind placebo-controlled trial. Journal of Herbal Medicine, 2017. 8: pp. 8–13.
17Mirmolaeea, S. T. et al., Evaluating the effects of Dill (Anethum graveolens) seed on the duration of active phase and intensity of labour pain. Journal of Herbal Medicine., 2014. 5(1): pp. 26–29.
18Culpeper, N., Culpeper's Complete Herbal. 1995: Wordsworth Press.
