The pH Factor (Part II)

Types of soil and their pH content

In the article ‘Bonsai soils’ there is a more descriptive analysis on the different types, but in short there are 6 basic soils:

Peat soils – are comprised of waterlogged partially-decomposed plant material including sphagnum moss, which is very high in organic matter and moisture with a pH starting approximately at 3.0

Sandy soils – contain the largest particles among the different soil types, that is dry, gritty and because there large are particles creating voids, water retention is not possible. However, sandy soil warms more quickly in the spring. Sandy soils have a pH starting at approximately 4.7

Clay soils – are the remnants of certain types of rocks eroded and weathered to form fine particles, that are high in nutrients, but they can be heavy, cold and wet in winter and very dry in summer. Clay soils have pH from 5.5 to 7.1

Chalky soils – are alkaline or lime-rich predominantly made up of calcium carbonate, they are indicative to particular landscapes including. The UK’s south downs and Wiltshire, Portugal, southern France and Spain. Chalk based soils can be either light or heavy and have a pH value from 7.1 to 8.0

Silt soils – are fertile, light and contain larger particles and are more moisture-retentive than sandy soils and drain more effectively than clay. But have a tendency to crack and crumble losing shape and structure; their pH range is approximately 6.5 to 7.

Loams – are mixtures that may include any of the above soil types depending on the needs of a particular species, albeit acidic, neutral or alkaline. For example, ericaceous plants including Azaleas genus Rhododendron family Ericaceae have a preference for higher acidity. Alternatively, Maples – genus Acer prefer a neutral soil composition, whereas the Burning Bush Euonymus alatus family Celastraceae require soil high in alkaline.

But, the acidic, neutral or alkaline content has great bearing on micro organism survival for example. Those found in acid and alkaline soils Acidophiles and Alkaliphiles respectively, are not as varied as the Neutrophiles found in neutral soil compositions. The pH range of 6.6 to 7.5 is more amenable to their needs in order to function. Generally speaking, there are four types of soil compositions including an all-purpose mixture for seeds, acidic, neutral and alkaline. Although they may vary according to the specific pH needs of a particular plant species.

Seed all-purpose mix – with this soil composition there are a lot of discussions as to which type is correct. Some will argue that the following mixture produces the best results:

3 parts organic matter, such as peat, humus or sawdust, 1 part sand, perlite, vermiculite or a combination of all three and 1 part sphagnum moss.
Others contend that seed soil mediums such as John Innes No1., Miracle-Gro, Levington or Thompson and Morgan, available ready mixed are perfectly capable of doing the job. But regardless of which type is preferred, all seeds require a form of stratification. (Described in the article The Stratification of seeds) Because this is the key to induce the embryo to germinate regardless of which soil composition is used albeit acid, neutral or alkaline. Moreover, it can be argued that seeds once stratified can germinate on a piece of damp kitchen paper, in a saucer of water or simply where they fall as shown below.

Scots Pine seedlings Pinus sylvestris

A good seed soil normally consists of heat-treated loam, sphagnum moss, peat, horticultural sand and fertilizers, which will last for approximately 30 days. After which the seedlings will need to be pricked out and transferred to a low nutrient soil mixture and left to develop. This soil composition slows down the growth rate allowing the plant to ‘put-on-weight’ meaning trunk and foliage development. It is also suitable for cuttings, which have taken root.

 
There are many types of seed soils available world-wide, in Finland a common mixture often used is ‘Musta Multa’, which roughly translated is ‘Black Mould’ a rich composition for most plant types. This product can be likened to the old but familiar ‘grow-bags’ where people who had no gardens or lived in apartments could grow vegetables in confined spaces. On its own this soil compost can be rather soggy if too much water is used, dissipating nutrients via water run off. To prevent this, a little sand, vermiculite, crushed clay or granite chips in the mix, which contain additional micro organisms usually solves this problem. It also allows air to flow through the medium permitting bacteria to function and although retains moisture does not become compact or waterlogged.

 
Acidic soil – The basic elements which cause acidity in soil are, the organic matter itself and the acidic mineral content within, which break down the matter through time making the soil acidic. Soil can also become acidic due to the loss of key minerals, potassium, magnesium, and calcium that have been leached out of the soil by excessive contact with water, thus the soil becomes acidic. This is a common phenomenon in peat bogs and pine forests and such soil is probably the best to use especially for conifers.

 
But before venturing out to obtain a sack full, which is going to upset the environmentalists and is also possibly illegal, there is a an easier method. Acid soil or Ericaceous soil to give the correct terminology is an entirely organic and peat-reduced compost, available at most horticultural establishments world-wide. Brands include, Thompson and Morgan, John Innes No 2., Bowers, Growise and Verve. Nonetheless, an ericaceous compost mix can lose its acidity over a period of time, depending on the amount used. For example, a large bonsai in a shallow pot will deplete the minerals more quickly than one in a deep pot.

 
Many horticulturists resort to using acidifying materials to counter this. For example such materials may include, pine needles or sphagnum moss placed on top of the soil allowing their acidic properties to penetrate to the roots. The use of Sulphur, Aluminium sulphate and Ferrous sulphate (sulphate of iron) are also used, but these may take some time to become effective, as they need to be broken down by the bacteria. Other methods are to use only rain water with white vinegar added (1 to 2 tablespoons in 4.5 litres or one gallon of water) as opposed to household tap water that has been treated with alkaline agents.

 

To make an ericaceous medium the following ingredients can be used;
Organic compost, sand, crushed clay or granite chips. The amount each of these components used depends on the acidic pH value one wants to achieve. Alternatively one can resort to using just Akadama, which many bonsai enthusiasts use for coniferous varieties, for example the Mugo pine Pinus mugo.

 

Neutral soil – is ready available from garden centres, department and hardware stores and can even be taken from your own garden. Of course the latter will need to be tested to ascertain the pH level, which may be in the region of 6.7 to 7.3 – slightly acid to slightly alkaline – a range that many species of plants can tolerate. But much depends on your particular region and temperate zone.

 

Arguably, there is no specific chart that states what type of ingredients should be used for this soil composition, as horticulturists world-wide have their own preference; what works for them. However, any neutral soil composition needs to be prepared to facilitate moisture retention, aeration and to allow the micro organisms to function, hence the use of grit, crushed baked clay pellets, sand, perlite or vermiculite and even bark chips can be used.

 
Alkaline soil – has a high saturation of soluble salts that are known as either sodic or saline with the former being dominated by sodium and the latter dominated by calcium and magnesium. Alkaline predominantly limestone is mixed with topsoil to produce a medium specifically for plants requiring a high pH level that can vary according to one’s particular needs. Manufacturers whom produce this product are for example, John Innes No3., Thompson and Morgan, Bowers and Rolawn. To make an alkaline soil composition, one can use the following ingredients.
Neutral top soil or prepared loam with a pH at approximately 7.0, clay or silt, washed grit and a lime additive. The amount of lime used will depend on the pH level one wishes to achieve. Tap water should be used as it is normally treated with alkaline agents.

 
The manufacturers instructions are wrong!“We did our research and followed the guidelines, all was fine in the beginning, but now the plant’s leaves are turning yellow and dropping.” Whether you purchased a ready-made soil composition or have mixed your own, it is doubtful that this is the cause for an unhealthy plant. Because reputable manufacturers even those mentioned above have been producing various soil mediums for generations that are tried and scientifically tested. Alternatively, if you have mixed your own soil composition, then you will probably know what ingredients to use and the proportional amount.

 
The possible causes for this down turn in the tree’s health is stress, which can be attributed to various factors. For example, inadequate drainage, no air circulation in the soil, damaged or compacted roots the latter known as ‘pot-bound’, the lack of nutrients, low light and an incorrect pH. These are the common causes why leaf tissue turns yellow referred to as chlorosis because, the essential green pigment chlorophyll is absent. Arguably the first course of action is to check the soil composition’s pH level, that can be found in the chart in part I of this discussion, which brings us on to the subject of soil pH testing methods.

 
Soil testing applications – for a true and accurate pH test of your particular soil medium one should opt for a laboratory test, but this can be expensive. Therefore, one resorts to purchasing various readily available test kits from the basic ‘2-test’ test kit (approximately 8€ to 13€ plus postage and packing) to the more expensive multi-test kits. (95€ to 350€+) Other devices for testing soil pH are in the form of meters both analogue and digital, some are purely for pH testing whilst other are multi-functional as shown below.

Soil pH test kits 5

But before venturing out to purchase a pH test kit, the question is – what type would be suitable and the factors to assist in this decision can be based on two simple questions:

1. The pH range for a particular plant species
2. Was the soil purchased from a horticulture outlet or a self-made composition

1. Most bonsai with the exception of some coniferous and deciduous species are able to tolerate a pH range from 6.7 to 7.3 and have the ability to prosper. For a more descriptive pH requirement for a particular species, refer to the chart in part I of this discussion.
But, any soil composition used in bonsai is an important concern, because this is where the plant receives the nutrients and moisture it needs to thrive.
2. If the soil used was purchased from a store or horticulture outlet, then information as to its composition and pH range will be written on the bag. Alternatively, if you mix your own soil composition/s using ingredients from various sources, then you will ultimately be changing the pH level, which needs to be checked. Therefore, the opening statement of ‘what soil pH test kit would be suitable’, boils down to two factors.

(a) Soil purchased from a reputable outlet will normally state its composition and pH level and even if we add grit, vermiculite, perlite, crushed baked clay etc, the pH level will not change that much. Therefore, investing in pH test kit is not really necessary nevertheless, it is an advantage to have a small one simply for peace of mind and to know what the pH level of a particular soil medium is.
(b) If mixing a particular soil composition using ingredients from various sources, then it is important to know the pH content of each component to ensure that the final medium is acceptable for the species; albeit acidic, neutral or alkaline. Therefore, investment in a testing kit is an advantage.

Soil test kits – Finding a suitable soil test kit does need some research as there are literally countless manufacturers all claiming their particular product/s produce/s the best results. They range from expensive laboratory equipment to analogue and digital probe meters, to relatively small cheap kits you can put in your pocket. The majority of these have been tried and tested with positive and negative results, that can be viewed via the world-wide-web. To give an indication as to the reviews, they have been condensed and listed as follows.

 
Litmus test – requires a small sample of soil mixed with distilled water in which, the paper is inserted for a few seconds. The paper’s colour change is then compared to those of a colour chart and an estimation of the soil’s pH is then determined. However, this method of testing is not very accurate, because it can only read a pH level in whole numbers for example 5.0, 6.0 and 7.0, which is an approximation. Therefore, as soil pH levels are measured in increments of both whole and half numbers for example 6.0, 6.5, 7.0 and 7.5 this litmus test approach is one to be avoided.

 

Chemical test – soil tests conducted by commercial laboratories are accurate in that they are able to determine mineral content and compound structures within a soil sample. For example, major nutrients nitrogen, phosphorus and potassium. Secondary nutrients sulphur, calcium, magnesium and minor nutrients; iron, manganese, copper, zinc, boron, molybdenum and chlorine. Such tests can be expensive, but for horticulturists wishing to use this method of testing there are products available. However, low cost ‘2 test’ test kits (top left image shown above) are only able to give an approximation of the pH level and that is the limit of their capability. Moving up the scale (top middle image shown above) are test kits able to determine the presence of major nutrients and are more accurate in reading the pH level. Alternatively, the test kit (top right image shown above) is able to search for both major and secondary nutrients, but has difficulty in ascertaining minor nutrients.

 

Analogue and digital meters – (shown in the above image) come in various forms from simple pH meters to multi functional probes able to test for moisture content, temperature, light quality and pH. Some manufacturers claim their meters are able to determine the presence of all nutrient categories, major, secondary and minor although this is debatable. Another argument concerning these multi functional meters is why test for moisture, humidity and light. Surely the horticulturist knows whether his or her bonsai has the right water content, knows the temperature/humidity at any given time and is aware of the plants position in relation to the light source.

 

For bonsai enthusiasts who use readily available soil mediums purchased from reputable outlets, a pH testing kit is not that essential. But for horticulturists making their own soil compositions, investing in a testing kit is advantageous as opposed to not. Because it allows for an accurate pH level to be determined correct for a particular species. If a pH testing kit is desirable then arguably preference should be given to those only dealing with soil pH levels as this is our primary concern. Not multi functional meters with reference to moisture, humidity and light content as these are unnecessary. But whatever test device you opt for, make sure it is suitable to your needs.

And finally, a message to O.T. known as ‘Tiger’ – I have some Maple (Acer) seedlings to give away if you are interested. Until next time BW, N.

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The pH factor (Part I)

The first signs of demise

Bonsai either given as a gift, individually purchased or one cultivated by other means, grafting, a cutting or from seed is usually lavished with care and attention to ensure its health and vitality. As the seasons progress new buds flowers and or fruit appear, enhancing the tree’s ruggedness and or beauty, a wonderful miniature specimen of its full size counterpart. But things begin to change, autumn is still a long way off, the tree’s leaves start to turn yellow and this is the first sign that something is not as it should be and questions start running through ones mind.

  • Was it watered enough or too much  
  • Was it given the correct type and quantity of feed
  • Should it have had full sun or partial shade
  • Has it been attacked by pests or disease
  • Did it need re-potting
  • Was it pruned at the wrong time of year

One then resorts to searching the world wide web looking for answers in trying to solve the problem/s, but how can we resolve the problem if we don’t know what it is. The above mentioned questions may have something to do with the tree’s poor state of health or potential demise, but not in every case. Arguably the main contributing factor causing a tree to wither and die is the medium or soil composition in which the tree is planted.

Acidic to alkaline

Soil contains a multitude of living organisms that consume, digest, and cycle nutrients. These living organisms include archaea, bacteria, actinomycetes, fungi, algae, protozoa, and a wide range of insects for example. Mites, nematodes, earthworms and ants all of which are important to the vitality of a soil composition, which in turn is vitally important to any and all growing mediums. But if these much needed organisms have expired, then the soil is effectively spent and of little use. However, the lack of organisms although of great importance is not the only issue, what is just as important is the type of soil composition and its pH content.

For example, some species such as Rhododendrons and Azaleas family Ericaceae will only survive in acidic soils. Whilst others the common Beech Fagus sylvatica and Hawthorn Crataegus laevigata prefer alkaline and some can be borderline, Cotoneaster family Rosaceae and Hazel family Corylaceae. But how do we know what kind of soil is correct for our particular bonsai? pH is measured from 1 to 14 and if we consider that a pH of 7.0 is neutral, all above will be alkaline and all below will be acidic, as shown in the following chart for the most common species found in bonsai.

 

pH chart.1

pH chart.2

pH chart.3

As the chart indicates most trees will survive in soil which has some degree of acidity up to a more neutral range, whereas others can tolerate a more alkaline based composition. To give a clearer definition consider the image below, which gives an indication of the acidic and alkaline values and the pH tolerance zone for most plants.

Soil pH graph

In the next article of ‘The pH factor’ (Part II) we look at soil differences, the possibilities of changing their pH content and a brief look at soil pH testing devices. Until next time BW, N.

The solo enthusiast versus the club member

Filming a silver birch wood recently a passer by enquired why, as the trees were devoid of foliage and looked rather ugly. The reply given was that some of the footage would be used to support a discussion on a pending bonsai article. As the conversation developed, he remarked that he had always been interested in bonsai and would like to know more about the art, now he had retired. “Are there any bonsai clubs or associations where one can join?” Unfortunately there are no bonsai clubs in this area that I am aware of was the reply. “That is a pity, bonsai are sold locally in garden centres and stores so there must be some interest.” Yes you are probably correct in your assumption, but it really is up to the individual whether he or she wants to be part of a club or stay as a solo enthusiast.

The solo enthusiast

For my part being a member of a club was not an option when my interest in bonsai began in the mid 1970s because, (a) my work meant much travelling with long periods away from home. (b) There were no clubs or associations in my then vicinity where one could gain the much needed knowledge. (c) Not having permanent roots and leading a nomadic existence is another factor. These are the reasons for remaining a solo bonsai enthusiast. Moreover, it can be argued that there is not much you can achieve as a club member that you cannot do as a solo enthusiast; you just have to work a lot harder.

Meaning that to gain bonsai knowledge, one has to immerse ones self in plenty of research for example. The attributes of a particular species of tree/s you may have and how to care for it or them, when to feed and what kind to use, when to prune and when to wire, preventing or eradicating pests and disease and the type of soil composition to use. At that time there were a few horticultural books and magazines to shed some light on these subjects, but there was no world wide web as we have today, so much of the work done was mainly trial and error.

However, now there are countless bonsai clubs and associations world-wide many accessible via the world wide web. All offering tips, tricks and advice from both the novice and the experienced through written text and production of video presentation, many of which can be found on Youtube – some good, some bad and some indifferent. The problem is that it takes time to trawl through it all to find what is relevant to ones needs without getting side tracked, which can be a real pain in the rear or a learning curve depending on how you approach the task.

Arguably the world wide web is very useful in that with one click of the mouse button, here is a site that has everything you need. From pre-bonsai specimens, soil compositions and fertilizers, ceramics, training pots, tools, various gauges of wire both copper and aluminium, cut pastes and wound sealants etc. But just going on line and purchasing what you think you need for example, a ready-made tool kit can be expensive, (100€ to 300€) only to find that improvisation using some standard DIY tools can reduce the cost considerably.

Another bone of contention is finding a reputable supplier who may not be in your area and the down side is the cost of postage, because bonsai equipment especially ceramics are relatively heavy. One can bargain for discount but, you usually have to purchase more than you need to get this. With ceramics, you see a pot listed that is presumably ideal for your tree, but when it arrives via the post it does not resemble its advertised picture. It looks awful when associated with your tree – now you are stuck with a pot you don’t want having paid good money for, which is now redundant – a hard and expensive lesson.

The club member

Being a member of a club or association, can reduce much of the hard work a solo enthusiast has to endure due to the pooled knowledge. For example one is able to receive information on the following subjects.

  • Care and general maintenance of bonsai

  • Advice on soil compositions and fertilisation

  • Styling, wiring and pruning, applying jin or sharimiki and uro

  • Prevention against pests and disease, how to make horticultural soaps

  • How to make basic tools and turntables via improvisation

  • Ceramics, how to choose the correct shape, size and colour

Moreover, a club is able to purchase different gauges of wire in bulk that can be sold at cost saving money. Initiate agreements with a supplier/s for example, the sale or return of ceramics and tools for either hand or power use. In addition, field trips can be organised, lectures and demonstrations from the experienced can be arranged. These are just some of the many advantages a club or association member has over the solo enthusiast.

What does it take to start a club?

It all depends on the level you want to start at, jumping in at the deep end will cost money you cannot recuperate. Stating off small is much easier, a few friends and or colleagues meeting once a month at a members house or apartment is a good way to start, failing this a coffee house or tea room will suffice. Advertising is always a headache and can be expensive especially if using the local press. One way to solve this is by word of mouth, putting adds on shop notice boards and if possible garden centres.

Another way is to make a web site, one does not need a degree in computer technology to achieve this as there are ready-made uncomplicated sites, able to accommodate your immediate needs. Such sites can be had for under 20€ for a years subscription and it is a way of putting the word out; getting known. Another consideration is to make a public presentation as an incentive to motivate new members to join. Such a presentation should be made by a member, preferably one with bonsai knowledge. The presentation should be short (10 mins) with time for questions and answers in addition, there should also be bonsai trees on display to aid the incentive.

Immediate needs

The club will need a chairman/woman to start and chair the meetings, which should be kept to a minimum leaving the majority of the allotted time for members to integrate. A secretary/treasurer who deals with the status quo and any new developments. All relative information can be channeled back to the members via email, rather than a printed format, which can be expensive and time consuming. A bank account for subscriptions and payments, the former to be agreed upon by the members.

As the club grows a venue will need to be found, preferably one free of charge, or one at low cost, because this is relative to the amount of each member’s subscription. Meaning, 12 x the monthly hire cost divided by the amount of members. A venue is important because it facilitates the need to accommodate such activities as discussions and demonstrations on bonsai horticulture, it also allows for members to meet and greet and share their knowledge. The exchanging of plants, cuttings and seeds, ceramics and other appropriate items, thus the club or association becomes a family.

A personal perspective

As stated, the bonsai club does have advantages over the solo enthusiast, but there is a more appropriate reason for its existence and it is for the following reason.

As we know nothing in this world lasts forever, even us mere mortals are part of the cycle of life. Our bonsai if cared for properly will undoubtedly out last us, but what then becomes of them once we shed our mortal coil. Will all the hard work, time and effort go to waste if homes cannot be found for them. Arguably one can sell them at auction where they are cared for by ‘green-fingered’ enthusiasts, which is the norm, but what actually happens to them is any ones guess. Going down this path fills me with trepidation, because those professing to be knowledgeable when they are not leaves a bitter taste in the mouth. What is more appropriate is to donate a bonsai collection to a club where they can be distributed among the members, whom will care for their health and continued development, which is a more appealing course of action.

The long dark cold days of winter are fading from memory as spring approaches, which for the bonsai enthusiast is when life begins anew, a time where our enthusiasm in bonsai is rekindled, not that it was ever diminished. It matters not whether one has only an indoor bonsai so called because of their temperate characteristics, a hardy outdoor species or a collection of both, the learning curve begins again. As stated the solo enthusiast has much work to attend, whereas the club member can reduce this considerably. Nonetheless, whatever your chosen path, success in your endeavours as bonsai enthusiasts is always tantamount. Until next time BW, N.

Toxic Bonsai Part IV

Toxic Bonsai Part IV

Umbrella tree (Queensland)Schefflera actinophylla. Family Araliaceae. Is an evergreen tree that grows to 15m (49ft) tall, native to the tropical rain forests of New Guinea, Java and Australia’s eastern Queensland. This decorative tree when mature, produces racemes up to 2m (6.5ft) long with an abundance of small dull red flowers beginning in late spring. Schefflera actinophylla is considered to be an aggressive plant prolific in growth, hence the reason why it is an uncommon specimen in bonsai collections. Schefflera actinophylla does contain toxins, but these are not considered to be dangerous to humans. Ingesting the leaves can cause mouth tingling and numbness, vomiting and abdominal pain and sap when in contact with skin can cause irritation and rash.

Umbrella treeSchefflera arboricola. (syn. Heptapleurum arboricolum) also a member of the Araliaceae family is native to Taiwan, but can be found world-wide as a house plant and also in bonsai. S. arboricola should not be mistaken for S. actinophylla, because of the height difference. Moreover, S. arboricola has different leaf colour and patterns some variegated with cream to white flowers with yellow edges or centres although much depends on the individual cultivar. S. arboricola is poisonous and carries the same toxins as S. actinophylla and leaf consumption can cause mouth tingling and numbness, vomiting and abdominal pain and sap when in contact with skin can cause irritation and rash.

ViburnumLantana. Family Adoxaceae. Also known as the ‘wayfaring tree’ is a deciduous shrub native to Europe, but can be found in Asia and northern Africa and is a relatively common specimen in bonsai. Its oval dark green leaves have a downy or hair like covering on the underside and flowers that are creamy white in colour and green fruit, which ripen to a bright red eventually turning black when mature. The berries if consumed although mildly toxic can cause vomiting, diarrhoea and abdominal pain if ingested in large quantities.

ViburnumOpulus. Family Adoxaceae. Is often referred to by its common name the ‘Guelder rose’ and is native to Europe, northern Africa and central Asia. This deciduous shrub has three lobed leaves that are opposite to each other having an appearance similar to maples. The flowers in clusters are white in colour with their centre being fertile surrounded by an infertile ring that are produced in early summer and fruit that is bright red. The berries if consumed although mildly toxic can cause vomiting, diarrhoea and abdominal pain if ingested in large quantities.

Virginia creeperParthenocissus quinquefolia. Family Vitaceae. Is native to north America, Canada, Mexico, Guatemala and Europe. It is a prolific deciduous climbing vine reaching heights of over 30m (100ft) and attaches itself to smooth surfaces by small adhesive pads. This plant normally seen growing on the sides of buildings has striking colours throughout the seasons, the leaves change from various greens to yellow to orange to red and purple and this colour change makes the species attractive to bonsai. The flowers are small and greenish white in colour, which change into purple/black berries in the autumn. The sap, leaves and berries are poisonous because they contain the toxin oxalic acid, prolonged skin contact can be dangerous and ingesting any part even small amounts can cause kidney damage and death to humans.

White cedarSpp. Family Cupressaceae. Include Chamaecyparis thyoides – Atlantic white cypress, Cupressus lusitanica – Mexican white cedar, Thuja occidentalis – Northern white cedar, Thuja plicata – western red cedar and Cryptomeria japonica – Japanese cedar. Cedars are conifers and are found in many parts of the world, from northern climes to temperate zones. They have many uses for example, grown as barriers, wind breaks, dense hedging in parks and gardens and are a common species in bonsai. However, all cedars carry toxins the primary irritant being plicatic acid and some are more potent than others for example, the western red cedar and Japanese cedar have the highest content. Exposure to plicatic acid can cause severe asthma, rhinitis or conjunctivitis, that can be progressive. In addition, plicatic acid in contact with skin can cause a hypersensitivity reaction, a type of response seen in tuberculin skin tests.

WillowSalix alba. Family Salicaceae. Is a species native to Europe but is also found in western and central Asia and within this genus are: Salix alba Vitellina – a willow with yellow shoots and Salix alba var. Britzensis, Cardinal and Chermesina having orange to red shoots. The willow a medium sized deciduous tree can be in a weeping form or with a dome shaped crown with long thin leaves pointed at the end. (5–10cm long x 0.5–1.5cm wide) It is often found in bonsai in designs that include slanting (Shakan) and (Fukinagashi) wind swept. Male and female trees each produce their own flowers in the form of catkins that appear in the spring and when mature are wind pollinated. However, the willow contain salicylate toxins in the bark that if ingested can cause the following. Ulcers, nausea, vomiting, stomach bleeding, kidney inflammation, tinnitus and skin rash.

WisteriaSpp. Family Fabaceae. Includes various species of climbing bines (Plants that climb by their shoots) Wisteria brachybotrys, Wisteria brevidentata, Wisteria floribunda, Wisteria frutescens, Wisteria macrostachya, Wisteria sinesis, Wisteria venusta and Wisteria villosa. That are predominantly native to the eastern north America, China, Japan and Korea. Although these species are found in bonsai, arguably the most common is the Wisteria sinesis that when in bloom has a striking floral display for example. The great wisteria at the Ashikaga flower park in Tochigi, Japan, which covers more than 1,990 square meters over half an acre. Wisteria flowers are between 10 to 80cm in length and produced in pendulous racemes and are either purple, violet, pink or white. All parts of the wisteria are poisonous they contain the toxin saponin and if ingested the symptoms are: nausea, vomiting, abdominal pain, diarrhoea, severe gastroenteritis, dizziness, confusion, speech problems and collapse.

Xanthorhizasimplicissima. Family Ranunculaceae. The only member of the genus Xanthorhiza, is native to the eastern states of north America. In the wild this shrub grows in sandy soil to a height of approximately 90cm. Its leaves are in a spiral configuration up to 18cm in length with flowers (6 to 20cm) that are produced in star shaped forms of reddish brown to purple. This attractive plant although used for ground cover in gardens, is uncommon in bonsai as its main stem does not produce a large girth. Xanthorhiza is poisonous, its contain the toxin berberine, which can cause nausea, dyspnoea, diarrhoea, nephritis, urinary tract disorders, skin and eye irritation.

Xanthocerassorbifolium. Family Sapindaceae. Native to northern China is a flowering and fruiting species of small tree growing to approximately 8m and can be seen in bonsai collections although uncommon. Its mid-green leaves 12–30cm in length are pinnate with flowers 10–20cm long containing 5 white petals arranged in panicle form, that appear in spring. The fruit a leathery pod splits open in three sections when ripe to reveal the black seeds, which resemble a small horse chestnut seed. Originally the flowers, leaves and fruits were eaten raw with little or no side effects evident. Nonetheless, it would be prudent for those with sensitive digestive systems to cook them before consumption.

YewTaxus Spp. Family Taxaceae. Yews are widely used in landscaping, ornamental horticulture and bonsai in which over 400 cultivars have been created including. The Japanese yew Taxus cuspidata, Pacific yew Taxus brevifolia and Canadian yew Taxus canadensis. All derived from the European yew Taxus baccata considered as Europe’s oldest living tree of which, a specimen can be found in St Cynog’s church yard in Wales dated to approximately 5000 years. The yew majestic and sombre in its appearance has a reputation as a harbinger of bad tidings for example. The yew tree often found in church graveyards as a symbol of sadness was also made into longbows, a weapon used in the battle of Agincourt 1415 by the English in their defeat of the French cavalry.

Yews are relatively slow-growing and can reach heights of 20m (66ft), with a trunk girth averaging 5m. (16ft) The bark is reddish brown with lanceolate, flat dark-green leaves positioned in a frond-like form on the stem. The fruit consists of a bright red cone called an Aril in which a single seed is contained, these are subsequently consumed by birds who disperse them via their digestive system.

All parts of the yew with the exception of the Aril are highly poisonous to humans as they contain the toxin taxane, that can cause the following if ingested. Low blood counts, arthralgias and myalgias, pain in the joints and muscles, peripheral neuropathy – numbness and tingling of the hands and feet. Hair loss, mouth sores, nausea, vomiting, diarrhoea and in some cases the results can be fatal. Moreover, male and monoecious yews in this genus release extremely small cytotoxic pollen, causing headaches, lethargy, aching joints, itching, and skin rashes and asthma.

Zanthoxylum – Kauaense. Family Rutaceae. Is a genus containing approximately 250 species of coniferous and deciduous trees and shrubs, indigenous to temperate and sub-tropical regions. It is known as the ‘prickly ash’ and is a common species in bonsai. The bark has limpet shaped protrusions containing sharp thorns at the centre, its bright green leaves are oval to oblong in shape with 6 to 8 in pairs on a single stem. The fruit are dull red berries tightly arranged in a cluster, that when ripe are used to make the spice Sichuan pepper. According to Asian herbal remedies, the bark was extensively used as a remedy for rheumatism, toothache and colic. Zanthoxylum is not considered poisonous to humans, but it does have the toxin Sesamin, which can cause digestive issues including, nausea, diarrhoea and abdominal pain. Other symptoms may include Anaphylaxis, an extreme case of allergy caused by Sesamin. All edible parts of the tree must be properly prepared prior to ingestion.

ZelkovaSerrata Spp. Family Ulmaceae. Often know as the Japanese or Chinese elm has two varieties, Japan and mainland eastern Asia Zelkova serrata var. serrata, and in Taiwan Zelkova serrata var. Tarokoensis. Z. serrata is a deciduous tree that in the wild can reach a height in excess of 30m (100ft +) and is favoured for its ornamental characteristics. A short fat trunk from which many branches radiate in a typical broom style. (Hokidachi) Its leaves are round to oblong in different shades of green, (Depending on the species) that change through the seasons to yellows, oranges and reds. The flowers in clusters are yellowish-green, which turn brown as they mature. Z. serrata a popular species is regularly found in bonsai collections. Z. serrata has in the past been used for herbal remedies including stabilising the womb during child birth nonetheless, it would be prudent to seek advice before ingesting parts of this species.

The trees and shrubs mentioned in this list are all toxic to some degree for example. In the beginning of the article part I information was given on the Acacia, a native of the African savanna, that have an abundance of thorns for protection. They also use poison in their leaves as a second line of defence against predation, predominantly from browsing wildlife.

Flora once indigenous to specific climate zones are now common place throughout the world in parks, gardens and bonsai, due to their discovery and availability. These species cultivated for their fruit and flowers and other various uses, all have some form of defence. Their toxicity ranges from mild, meaning having little effect on humans and domestic pets, to being potentially fatal.

As to a particular species’ poisonous capabilities we are basically unconcerned, probably due to its benign appearance or attractiveness and addition to a bonsai collection. Nonetheless, this article was written in order to shed some light on floral toxicity and the potential hazards that exist. But it does not mean we should take to wearing protective apparel. Even the most toxic of bonsai specimens, the Yew – Taxus can be handled, providing we refrain from ingesting any part of it and ensuring that any body part in contact, predominantly the hands and the tools we use are thoroughly cleaned.
Until next time BW, N.

 

Toxic Bonsai III

Toxic Bonsai Part III

NandinaNandina domestica. Family Berberidaceae. A common colourful species used in bonsai is not a bamboo plant as it is often referred to, but an evergreen shrub growing to 2m (7ft) tall by 1.5 m (5ft) in width. In springtime new leaves are a bright pink, which turn a glossy green. The flowers are white and in clusters, with fruit in the form of a bright red berry. All parts of this tree are poisonous as it contains compounds that produce hydrogen cyanide, which could be potentially fatal if ingested. Although there are those who claim the tree is non-toxic to humans, ascertaining if there is any truth to the argument is not worth the risk.

NeeaNeea buxifolia. Family Nyctaginaceae. Often referred to as the flowering tropical boxwood, this tree is a native of Puerto Rico. It is a rather twiggy specimen with a large diameter trunk with small long narrow oblong leaves, with new shoots appearing in dark red, flowers and red fruit. No part of this tree should be ingested as it belongs to the Nyctaginaceae family, in which many members such as the Bougainvillaea another favourite in bonsai are poisonous. Symptoms are similar to that of poison ivy and may include, pain, itching or burning skin, blisters and dermatitis.

NutmegMyristica fragrans. Although uncommon in western bonsai collections, can be found in more temperate climes. The problem with Nutmeg seed propagation is that there is no way of knowing once germination has taken place if the plant is male or female. Because this species is dioecious and male trees are unproductive, the common way if one desires a female fruiting tree is to either graft, patch bud or air layer. The Nutmeg although widely use for culinary uses contains the toxin myristicin, a monoamine oxidase inhibitor and psychoactive substance. If ingested in large quantities can induce convulsions, palpitations, nausea, dehydration, and generalized body pain.

OakQuercus. Family Fagaceae. A deciduous and evergreen tree with a variety of species that include, white oak Quercus alba and stone oak Lithocarpus. Oak leaves and acorns are poisonous as they contain tannic acid, which can cause kidney damage, gastroenteritis and diarrhoea in livestock for example. Sheep, goats, horses and cattle, but it has little effect on the domestic pig. It is said humans are not affected providing the tannins have been removed nonetheless, those with sensitive digestion systems should avoid consumption.

OleanderNerium. Family Apocynaceae. A small tree or shrub having approximately 400 different varieties in the genus Nerium can be found in many temperate zones throughout the world. It is widely cultivated as an ornamental plant for parks and gardens reaching heights of 2 to 6.5m. (19ft) Although there now exist many dwarf varieties, which only grow to 26cm (10 ins) and these can be found in some bonsai collections. Oleander when mature has grey bark, with dark green thick leaves arranged in pairs that are relatively narrow in shape. The flowers from white to pink to red are highly scented although much depends on the variety and fruit in a long pod, which when ripe open to reveal large amounts of seed. Oleander although a very attractive plant, is considered extremely poisonous as it contains the toxins oleandrin and oleanrigenin that are referred to as cardiac glycosides. Ingesting any part of an Oleander can cause serious gastrointestinal problems; nausea, vomiting, excess salivation, abdominal pain and diarrhoea. Other reactions to Oleander glycosides include cardiac and central nervous system effects; an irregular or erratic heart rate and drowsiness, muscle tremors, seizures and collapse that can have fatal consequences.

OliveOlea europaea. Family Oleaceae. Olive trees are not toxic and ingesting the fruit has no known side effects. However, olive tree pollen is extremely allergenic and according to the Ogren Plant Allergy Scale, a rating system for plants measuring their potential to cause allergic reactions in humans, it has a rating of 10 out of 10. And as the olive tree is wind-pollinated the pollen if inhaled, can cause headache, blocked sinuses, breathing difficulties and serious asthma attacks.

Orange jasmineMurraya paniculata. Family Rutaceae. A tropical evergreen tree or shrub from Asia is a common specimen for bonsai. It has glossy leaves and white scented fragrant flowers that can remain throughout the growing season and fruit ranging from orange to red, resembling the kumquat. The orange jasmine has no known toxins harmful to humans, but the flowers are highly allergenic and can cause headache, blocked sinuses and breathing difficulties and in some instances severe asthma.

PlumPrunus Spp. Family Rosaceae. Is a diverse group having many species between 19 and 40 according to taxonomists. Arguably the most common plum trees used in bonsai are the European plum Prunus domestica and the Japanese plum Prunus salicina. The flowers are fragrant and vary from white to cream, to various shades of pink. The fruits are usually globose to oval between 2cm to 6cm in size with firm flesh surrounding a hard seed pod. Plum seeds contain the toxin cyanogenic glycosides including amygdalin that decompose into a sugar molecule resulting in the production of Hydrogen cyanide gas, which is extremely poisonous and flammable.

PodocarpusPodocarpus neriifolius. Family Podocarpaceae. There are approximately 97 to 107 species in the genus that are related to conifers and can be found in bonsai collections. Podocarpus are evergreen with cones forming a brightly coloured fleshy, berry-like receptacles inviting birds to feed and in so doing the seeds are dispersed through their digestive tracts. Podocarpus are also related to yews, thus their leaves, stems, bark and pollen are cytoxic. In spring and early summer, the male Podocarpus blooms and releases the cytotoxic pollen and exposure to this can create an effect mimicking the cytotoxic side effects of chemotherapy, where blood cells or bone marrow are most at risk of developing serious infections.

Privet­ – Ligustrum vulgare. Family Oleaceae. A species native to Europe, Australia, Africa and Asia is commonly used in bonsai. Species include the Japanese privet Ligustrum japonicum, Chinese privet Ligustrum quihoui, which are mainly used for ornamental plants and Ligustrum ovalfolium for hedging purposes. The latter if managed regularly is quite decorative, but if left to its own devices will become unruly. Privet leaves and bark have bitter properties, which in China are used for making herbal teas. However, privet species that yield fruit should not be ingested as they are toxic; symptoms include nausea, headache, abdominal pains, vomiting, diarrhoea, low blood pressure and weakness.

QuinceCydonia oblonga Family Rosaceae. Include such species as Chaenomeles japonica and Pseudocydonia sinensis that are small deciduous fruit and flowering trees. The flowers borne in clusters vary according to the species from pale pink to red and both species bear fruit in the form of a pome, which is bright golden-yellow at maturity. Although the fruit is edible, it is astringent and can cause a shrinking or constriction of the body tissues for example, a dry puckering of the mouth due to the tannins present. The quince has been used for both culinary and medicinal purposes but it is poisonous, as the seeds contain nitriles that if ingested will be hydrolysed by the stomach acid producing hydrogen cyanide.

RhododendronSpp. Family Ericaceae. Contains approximately 1,024 species of trees and shrubs both evergreen and deciduous and found throughout the world, from north America, Europe and Asia. They are a common addition to any bonsai collection due to their colourful showy flowers that bloom from late spring to early summer. All rhododenron species including, Rhododendron obtusum, Rhododendron simsii, Rhododendron indicum and Rhododendron luteum are poisonous. They contain Andromedotoxins that are water-soluble diterpenoid compounds in the leaves flowers and nectar. If any part of the plant is ingested symptoms include, salivation, a burning sensation in the mouth, emesis, diarrhoea, muscular weakness, impaired vision and dyspnea. Hypotension and atrioventricular block, a serious cardiovascular effect that may have fatal results.

Rosary PeaAbrus precatorius. Family Fabaceae. Known by other names including the ‘Jequirity bean’ is native to warm and tropical regions and also found in bonsai. Those with children and domestic pets are advised not to keep such a plant due to its very nature. This species with its frond-like leaf formation and bright red fruit is extremely poisonous as it contains the toxin abrin. Abrin is similar in structure to ricin the toxin in Ricinus communis or ‘Castor bean’ plant and some claim that abrin has a higher toxicity level. Abrin is found in all parts of the plant but, it is the seeds that attract the most attention and if crushed, chewed and ingested abrin is released and can be fatal.

RowanSorbus aucuparia. Family Rosaceae. Native to the northern hemisphere are also found in more temperate climes including Africa and Asia. Its growth can be prolific portraying grey bark, compound frond-like leaves and scented flowers white to cream, and orange to red berries. And this combination makes the species very attractive to bonsai collectors. Nonetheless, rowan tree berries are poisonous as they contain parasorbic acid, which is used as a food preservative and in cosmetics. Symptoms can include, eye and respiratory problems, skin irritation and abdominal pain. However, if they are cooked the parasorbic acid is transformed into sorbic acid, which is not poisonous if ingested.

SnowberrySymphoricarpos alba. Family Caprifoliaceae. Also know as the ‘ghost berry’ and ‘wax berry’ a genus of approximately 15 species native to north America are found in other parts of the world. They are members of the honeysuckle family Caprifoliaceae and are used in bonsai for their fragrance and decorative flowers and coloured fruit, white, pink and red depending on the species. The white berries of Symphoricarpos contain the following toxins, viburnin, chelidonine, saponins, tannins, terpenes, tryglycerides and coumarins. If ingested the symptoms are vomiting, blood in urine and delirium. However, the toxic combination has a powerful emetic effect – a gastrointestinal irritant, which causes the victim to expel the berries undigested.

Spindle treeEuonymus europaeus. Family Celastraceae. A native to Europe is a deciduous tree or shrub noted for its colour changes during the season. It has leaves that change from dark green to yellow to red to purple and flowers yellow to green grown in clusters. The fruit, which can be pink, red or purple when ripe open to reveal its orange coloured seeds. This colour change make it a popular specimen for bonsai. But the fruits are poisonous containing a cocktail of toxins including, alkaloids theobromine, caffeine and terpene. Poisoning in children is quite common as the brightly coloured fruits are attractive. Ingesting the fruit can cause liver and kidney damage and can be fatal.

SpurgesEuphorbia Spp. Family Euphorbiaceae. This genus has over 500 species of trees and shrubs including Euphorbia tirucalli, a tall growing shrub native to semi-arid tropical climates. It has a wide distribution throughout Africa and is common in the dry states of north America in particular California. In bonsai E.tirucalli is not one of the most favoured of specimens although it can be found, because of the problems of shaping and pruning. For example, merely cutting a branch or twig causes the plant to ooze a sticky white toxic latex. This latex when in contact with skin is extremely irritating causing redness and a burning sensation. If in contact with the eyes the result is severe pain and temporary blindness. If ingested symptoms are burning to the mouth, lips, and tongue and can be fatal.

TamaracLarix laricina. Family Pinaceae. Known as the black, eastern, red and American larch, is native to north America and Canada and is coniferous and deciduous due to its needle leaf structure that is shed in the autumn. The Tamarac has more medicinal qualities as opposed to toxicity for example. Tea made from the bark was used as a laxative, a remedy for rheumatism and skin ailments. However, this species is prone to attack from the fungal pathogens including Lachnellula willkommii and contact with it should be avoided. It is also argued that oil from the leaves in contact with the skin can cause dermatitis nonetheless, it is a popular species found in many a collection.

TitokiAlectryon excelsus. Family Sapindaceae. Formerly known as the New Zealand oak is as its name suggests native to this antipodean realm. Like its European counterparts it has a twisted trunk with branches radiating in all directions and its apex is formed into a canopy. Its flowers are relatively small and purple in colour and its fruit are a pinky-grey capsule that when ripe, open up to reveal a bright red pulp with a black seed. The Titoki seen in some bonsai collections is poisonous, because it contains tannins and cyanide-producing poisons in its bark, leaves and fruit that if ingested can cause; vomiting, gastroenteritis, diarrhoea, delirium, kidney failure and at worse fatality.

Tea tree (Chinese)Camellia sinensis. Family Theaceae. Camellia sinensis is an evergreen shrub that if left to its own devices can grow in access of 5 metres (16ft) in height. Producing white flowers with bright yellow stamens surrounded by glossy green leaves and fruit having a hard green shell and a single brown seed contained within. There are many cultivars of the tea tree that are used to make a refreshing beverage partaken by countless individuals including, the Camellia sinensis assamica (Assam, India) strain. Nonetheless, the tea tree is considered poisonous because it contains caffeine and tannin toxins that are addictive. It is argued that consuming five cups a day are sufficient to produce addiction and reduced intake or withdrawal can cause; dizziness, headaches, palpitations, indigestion, constipation and insomnia. Moreover, excessive intake or over indulgence can be harmful to pregnant women.

In toxic bonsai part IV we will conclude the alphabet on toxic bonsai, until then BW, N.

Toxic Bonsai II

Toxic Bonsai Part II

Ginkgo biloba – Family Ginkgoaceae. Also known as the maidenhair tree native to China is the only living species in the division Ginkgophyta, as all others are now extinct. Its fruit is used for culinary purposes and in traditional Chinese medicine and is considered by some to contain aphrodisiac properties. However, the seed pulp has toxins that are not destroyed when cooked and if eaten in large amounts poisoning by methyl pyridoxine, (neurotoxin) can cause epileptic seizures. In addition, the sarcotesta or fleshy seed coat is poisonous and disposable gloves are required as they are able to cause dermatitis and or blisters. Other side effects include; nausea, vomiting and diarrhoea.

Guelder roseViburnum opulus. A deciduous shrub can be found in woods, hedges and in areas containing a lime-rich soil compound. The tree has large white flowers with smaller yellow ones on the inner part of the cluster, the white flowers are infertile whilst the yellow ones are fertile. In autumn the flowers produces red berries with a single seed in each. All parts of the tree are poisonous to humans as they carry toxins such as iridoid glycoside, isobutyric Acid, coumarins, tannins and saponins. These can cause severe nausea, vomiting, diarrhoea, swelling and over heating.

Grevillea robusta – Family Proteaceae. Commonly known as the Australian silver oak although uncommon can be found in European bonsai collections. This evergreen tree with its feather like leaves similar to a fern frond is known for its prolific growth and produces golden orange blooms. The flowers and fruit of G. robusta are poisonous, they contain hydrogen cyanide sometimes referred to as Prussic acid and tridecylresorcinol responsible for severe contact dermatitis.

Honey LocustGleditsia triacanthos. Is not a toxic tree unlike its ‘look-alike’ counterpart the black locust, Robina pseudo which is extremely poisonous. The two species can be identified as follows: the black locust has wisteria like flowers and small black seed pods, whilst the honey locust has small clusters of flowers and long seed pods 15–20 cm. Honey locust trees have extremely sharp thorns 3 cm to over 20 cm protruding from the branches, that harden and turn red as they age, then fade to grey becoming brittle as they mature. As a result the honey locust is considered difficult to wire and shape although thorn less varieties (Gleditsia triacanthos var. inermis) are occasionally found growing wild and are available as nursery plants. But there is no guarantee they are free from toxins.

HollyIlex. Family Aquifoliaceae. There are 400 to 600 species ranging from evergreen to deciduous trees and shrubs, found in temperate to tropical climates around the world with many shaped into bonsai. The bark is relatively smooth with small nodules known as ‘warts’, the glossy oval leaves are dark green in colour. Holly is dioecious meaning that the flowers of male and female are peculiar to their own sex and tree. These flowers 4 white petals when mature become scarlet berries and are attractive to birds, whom ingest them, but pass the seed through their digestive system intact. However, for humans they are predominantly poisonous as is the rest of the tree. Holly contains such toxins as caffeic, feruloylquinic, chlorogenic and quinic acids, kaempferol, tannins, rutin and theobromine compounds found in all parts of the plant. Holly berries can cause severe vomiting, diarrhoea and nausea that can be fatal for young children if consumed.

HawthornCrataegus. Family Rosaceae. Is a species quite common in bonsai grown for its floral display. The flowers are hermaphrodite, meaning both male and female reproductive parts are contained within each flower. Flowers are highly scented, white or occasionally pink with five petals, and grow in flat-topped clusters, with small pome fruits and thorny branches. Although hawthorn fruit is not toxic if used in herbal remedies and culinary purposes it must be prepared properly. Failure to do so can cause nausea and sedation, cardiac arrhythmia and dangerously low blood pressure if taken in large quantities. Those taking digoxin a medication used to treat various heart problems should avoid hawthorn completely.

Indian PeaLathyrus sativus. Family Fabaceae. Although not really considered as bonsai material, is often cultivated for its striking blue flowers, but more importantly as an insurance against famine in third world countries where drought is a major problem. The crop is harmless to humans if ingested in small quantities occasionally, but continuous intake over a prolonged period (3 months) can have serious side effects. The plant produces seeds containing diaminopropionic and neurotixic amino acids and can cause a disorder known as lathyrism. A neurodegenerative disorder causing paralysis of the lower body, emaciation of gluteal muscle and brain damage in children.

Idesia – Family Salicaceae. A tree not normally found in western bonsai collections is common in its native regions of China, Japan, Korea and Taiwan. It is a deciduous tree with greyish-green bark and heart shaped dark green leaves 8 to 20cm in length protruding from a red petiole. Flowers are small, fragrant and yellowish green in colour. The fruit of the Idesia is a small orange berry, which ripens to dark red almost purple in colour, that can be consumed, but as with all wild fruit care should taken in its preparation prior to ingestion. Idesia has no known toxins that are harmful to humans.

Incensed Cedar – Libocedrus decurrens. Family Cupressaceae. Is a popular species for bonsai as formal, informal and literati styles. It contains strong volatile oils including thujone, a ketone that is known to be toxic in large quantities and it is best known as a chemical compound in the spirit absinthe. Thujone has a menthol odour and is considered toxic to the brain, kidney, and liver cells and could cause convulsions if used in too high a dose. It should not be used during pregnancy, breastfeeding or those with kidney weakness.

JacarandaJacaranda mimosifolia, Family Bignoniaceae. Has been cultivated in many temperate parts of the world and also in bonsai thriving in sandy soils with full sunlight. Young trees are unable to withstand cold conditions, but mature specimens are able to tolerate temperatures down to -7°C (19°F) for brief spells. The jacaranda is known for its stunning display of flowers produced in large panicles, with colours ranging from blue to purple and fruit in a flattened oblong pod containing the seeds. Nonetheless, the Jacaranda is said to be toxic, exposure to the pollen can cause skin irritation and rash. Ingesting either and or flowers and seeds can result in, vomiting, nausea and abdominal pain.

Jade treeCrassula ovata. Family Crassulaceae. Has other common names including, ‘Friendship tree’, ‘Money tree’ and ‘Lucky plant’ and is native to south Africa and Mozambique and is found throughout the world as a common house plant. Arguably, C. ovata is not a true tree in the sense of the word, meaning it does not shed its leaves or needles on an annual basis as deciduous and conifers do. It is a succulent, a water retaining plant that has the ability to thrive on limited water sources. Whereas most conifers and deciduous trees require a constant supply of water that is continuously pumped through its system. In addition, its trunk and branches never become true lignified tissue, they remain soft and fleshy during the plants life. Nonetheless, it is found in many bonsai collections with some attractive results. C. Ovata has rich jade green thick, shiny, smooth, leaves growing in opposite pairs along the branches. Some varieties may have a yellowish-green appearance, whilst others have a red tinge on the edges. The flowers of C. Ovata under the right conditions are small star-like white or pink flowers arriving in early spring. The jade plant is poisonous to domestic pets (dogs and cats) and marginally toxic to humans and if ingested may cause vomiting, diarrhoea, abdominal discomfort, loss of appetite and lethargy.

JasmineGelsemium sempervirens. Family Gelsemiaceae. A relatively common species found in bonsai collections for its individual trumpet shaped yellow flowers, that are strongly scented and appear on the tree prior to the production of new growth. However, all parts of this species are poisonous containing toxins such as strychnine related alkaloids and gelsemine a highly toxic compound that acts as a paralytic and often results in death. In addition, the sap from this plant can cause severe problems if in contact with those having sensitive skin causing rash and swelling.

JuniperSpp. Family Cupressaceae. This order has many species widely used in bonsai horticulture and it is argued that they are all toxic due to the volatile oils found within the plant. Alpha-pinene, myrcene and sabinene, which if ingested can cause diarrhoea, nausea and hypertension. Although considered by many to be safe for culinary uses, juniper berries if consumed on a regular basis can cause cause serious kidney damage. Pregnant or breastfeeding women are advised to refrain from usage due to the risk of miscarriage. Those taking Telmisartan a prescribe drug, which is used to treat high blood pressure (hypertension) should refrain from ingesting any part of this plant.

Kentucky coffeeGymnocladus dioicus. Family Fabaceae. A species native to north America is also used in bonsai. Its rough ash-grey bark similar to that of oak can fall or peel away from its surface leaving scarring and indentations, which adds character to the tree. Its flowers are dioecious and has fruit in the form of a hard-shelled bean in pods from 13cm to 25cm. (5 to 10 inches) The seeds are considered poisonous as they contain the toxic alkaloid cytosine, that if consumed can cause respiratory difficulties, which can have fatal results. However, it is argued that if the seeds are roasted, the cytosine is neutralized, but for those with respiration problems it is not a risk worth taking.

KumquatFortunella japonica. Family Rutaceae. The species has no known toxins harmful to humans and is usually grown as an ornamental plant, but is found in bonsai collections. The fruit resembles a small orange a little larger than a grape, its peel has a sweet flavour whilst the inner pulp is sour but is edible when cooked. It is also ingested in its raw state, but those with a sensitive digestion system should refrain from doing so due to the concentration of oils (Limonene) and acids within the fruit. Which can cause diarrhoea, nausea and other abdominal complaints.

KurrajongBrachychiton populneus. Family Malvaceae. Is native to Australia and found in various habitats from wet coastal districts to semi-arid regions. The bell-shaped flowers range in colour from pale cream to pink with simple pointed shaped leaves. The seeds are covered in small stiff irritating hairs, which have to be removed prior to roasting and ingesting as they contain toxins. Although these are not considered dangerous to humans they can be to domestic pets, sheep and cattle causing lameness, tremors, collapse and in some cases fatality depending on the victims disposition.

Laburnum – Family Fabaceae. Is a genus of two species of trees that are Laburnum anagyroides known as the common laburnum and Laburnum alpinum the alpine laburnum. They are often found in bonsai collections due to their colourful yellow pea-like flowers. That are in pendulous leafless racemes 10–40 cm (4–15.5 in) similar to the wisteria, making them very popular trees. However, all parts of the tree are poisonous; roots, bark, wood, leaves, flower-buds, petals and seeds as they contain the toxin cytosine a nicotinic receptor agonist that produces a biological response. Symptoms may include intense lethargy, vomiting, convulsion, coma and severe diarrhoea.

Laurel (Cherry) Prunus laurocerasus. Family Rosaceae. Is a shrub often used for topiary in hedging and also in bonsai as it is easily shaped. The leaves are a shiny dark green with creamy white flowers and fruit that turn black when ripe. The whole plant is poisonous containing the toxin hydrogen cyanide, also known as prussic acid and identifiable by its strong almond-like smell and bitter taste. Symptoms can include breathlessness, weakness, spasms, convulsions, coma and respiratory failure.

ManchineelHippomane mancinella. Family Euphorbiaceae. Classed as an endangered species is a flowering and fruiting tree native to Florida, Mexico and the Bahamas growing among mangroves and in coastal waters. Its fruits are green and round resembling a small apple, hence its common name the ‘Beach apple’. H. mancinella is an evergreen tree with reddish-grey bark, glossy oval green leaves, greenish-yellow flowers and grows to a height of approximately 15m. (49ft) It is also known in Spanish as ‘Manzanilla de la muerte‘, the ‘Apple of death’ and is considered one of the most dangerous trees in the world. All parts of the tree are extremely poisonous with arguably the sap being the most toxic as it contains phorbol a member of the tiglian family of diterpenes. Even the smallest amount diluted in water can cause severe blistering of the skin and ingesting the fruit can cause intense gastrointestinal problems that can have fatal results. Manchineel is cultivated for its timber source, but little is known of its use in bonsai.

MistletoeViscum album. A hemiparasitic plant in the order Santalales. A mistletoe seed attaches itself to a tree by a structure called the haustorium and is able to germinate independently, but as it develops it penetrates the branch of its host absorbing nutrients and water. The European mistletoe has evergreen leaves in pairs with waxy white berries in clusters of two to six, that contain the toxins polysaccharides, alkaloids, and lectins. Which can cause blurred vision, nausea, abdominal pain, diarrhoea, blood pressure changes that can be fatal. Those taking Telmisartan a prescribe drug, which is used to treat high blood pressure (hypertension) should be aware of potential problems. Mistletoe is found in bonsai, but is uncommon as it can affect other species within a collection.

Mock orangePhiladelphus coronarius. Family Hydrangaceae. A species of flowering plant native to Southern Europe is a deciduous shrub growing to approximately 3 m tall by 2.5 m wide and often found in bonsai collections. What makes this a popular collectable species is because of its bowl-shaped double white flowers on prominent stamens, that are highly fragrant. The ‘toothed’ dark green leaves turn to yellow in autumn adding more colour to the plant. Yet the seeds and flowers carry toxins that although considered mild and not life threatening, can cause nausea, vomiting, diarrhoea and skin rash if consumed. But much will depend on an individual’s digestive system.

MyrtleMyrtus communis. Family Rosopsida. A common species found in bonsai has reddish brown bark that is apt to peel off in mature plants. The flowers usually white in colour have five petals and numerous long stamina and can be heavily scented. The leaves are small, narrow and dark-green and filled with oil, which is visible as small dots when held against a light. This oil is slightly toxic and may cause headaches, nausea, indigestion, and may colour urine purple if consumed in large quantities.

In toxic bonsai part III we continue the discussion on species ‘N’ to ‘T’ until then BW, N.

Toxic Bonsai I

Toxic Bonsai (Part I)

In the early days of bonsai horticulture tree varieties included the Juniper JuniperusSpruce Picea Pine Pinus and Larch Larix. As time progressed, more species were added for example, flower and fruiting varieties Wisteria Floribunda and Azalea genus Rhododendron, in the genus Prunus plum, cherry, peach and apricot. Today many other species from around the globe have now become part of bonsai horticulture including those which may be considered as common, the European Horse Chestnut Aesculus hippocastanum the unusual Acacia genus Acacia and the exotic, the Madagascar Euphorbia milii described below.

Many bonsai enthusiasts either have traditional collections predominantly coniferous, whilst others prefer deciduous and some will have an assortment of species. These artistically shaped miniature trees portray delicate, graceful and rugged forms and although their beauty is beholding, all is not what it seems. These little adaptations are able to produce toxins just as their full-sized counter parts can, which have the power to incapacitate all fauna including humans even to the point of being lethal.

All flora have developed ways to defend themselves, from the production of toxins in their leaves, fruit and seeds to the emittance of gas and or extremely sharp thorns which deter most from ravaging their foliage. The European Horse Chestnut Aesculus hippocastanum a large deciduous tree has greenish-yellow to white flowers and fruit contained in spiny capsules. In the UK at autumn time children collect the fruit capsules and remove the seeds from within, thread them on lengths of string and participate in an old traditional game of ‘Conkers’. A game dating back to 1848 where turns are taken in striking each others ‘conker’ until one breaks; yet the players who take part in this ritual, are probably unaware that these ‘conkers’ or seeds are poisonous.

common-horse-chestnut

Acacia genus Acacia, of which there are approximately 160 species of trees and shrubs within the pea family Fabaceae are native to Africa and Australia. Those of the African savanna have an abundance of thorns for protection, but also use poison in their leaves as a second line of defence. When the tree is disturbed it pumps poison into its leaves releasing ethylene gas from the pores. This gas release if detected by other acacias in near proximity sound the alarm alerting them to a potential threat and in so doing they too inject poison into their leaves.

the-acacia

The Madagascar Euphorbia milii commonly known as the Crown-of-thorns – a shrub with flower clusters and red, petal-like bracts has thorns that are poisonous. These thorns if damaged secrete a latex sap called urushiol and when in contact either on or under the skin can cause a sumac rash a very serious allergic reaction; a form of dermatitis.

the-madagasacar

Perhaps the question on most peoples lips is why would you want to have a tree that is poisonous? The question can be answered in two ways (a) why do people keep exotic pets, arachnids such as the Mouse Spider Missulena, which is every bit as dangerous as it looks or a Burmese python Python bivittatus that can be extremely aggressive. Pterois, or lion fish with its showy pectoral fins and venomous spiky fin rays, a popular choice among marine aquarists. It is really down to human nature, some are content to have the mundane household ‘moggy’ (cat) as a pet, whilst others want something which can be seen as diverse. (b) It is possible that somebody was given a bonsai as a gift without the purchaser bothering to research the tree’s attributes, it just looked nice. Furthermore, most bonsai contain toxins of one sort or another in their defence that vary in type and amount.

There are countless species of flora that exist on the planet including wild or natural varieties and hybrids, the latter pioneered by Gregor Mendel whom is credited with starting the hybrid plant revolution with his genetic studies of peas in the early 1900s. And least we forget those that have been genetically modified to produce more flower and fruit and combat insect infestation. To describe the peculiarities and properties of flora is a monumental task and narrowing it down specifically to bonsai, would amount to a PhD thesis. Therefore, the discussion will be further refined focussing on bonsai that can be found in most collections either common or unusual. The complete topic will be in four parts this post being part I and arguably the most efficient way in undertaking this, is to list them in alphabetical order.

Acer – Family: Aceraceae. The toxins are found within the leaves which increase as they wilt and die. It is also found in the seeds although the content is less. The acer although not harmful to domestic pets and humans is potentially fatal to equines if ingested as the poison damages red blood cells, diminishing their ability to carry oxygen. Death can occur from between 18 hours to 10 days.

AppleMalus Spp. The seeds are mildly poisonous and contain a small amount of amygdalin a cyanogenic glycoside that play important roles in many plants including apple varieties. However, the amount of cyanogenic glycoside contained within the seed is not considered dangerous to humans nonetheless, ingesting a large quantity can provide severe side effects.

Alder BuckthornRhamnus frangula L. This tree or shrub found among hedgerows, along roadsides and in woodlands, has a number of toxic chemicals, including emodin that are within its bark and purple-black berries or fruits. Emodin is a purgative resin, which is also found in rhubarb and also produced by many species of fungi. If ingested the symptoms are: collapse, convulsions, diarrhoea, gastroenteritis, haemorrhage and vomiting.

Azalea – genus Rhododendron Family Ericaceae. Is a common species that appear in bonsai collections but, it is poisonous. The toxins Grayanotoxin and arbutin glucoside are found in all parts of the plant the flowers, leaves and nectar – the latter often referred to as ‘mad honey’. They can cause nausea, vomiting, weakness, dizziness, breathing difficulties, low blood pressure, reduced heart rate and irregular rhythm, which could be life threatening.

Beech – genus Fagaceae. Indigenous to Europe, Asia, and North America produce a triangular shaped fruit called beechnuts in the autumn. These nuts often used as a food source are high in tannins having a strong bitter taste and are toxic to both canines and humans especially children if consumed in large quantities. The European beech Fagus sylvatica, is believed to be more toxic than its the American relative, Fagus grandifolia. Symptoms include; vomiting, diarrhoea, abdominal pain, nausea, fatigue and dilated pupils – mydriasis.

BirchBetula Spp. Has more homeopathic properties as opposed to toxins nevertheless, pollen from the silver birch, Betula pendula, is the second most severe allergen for people as it can travel many kilometres via the wind. It is able to cause hay fever, conjunctivitis and severe respiratory problems with disease to the lungs and asthma. Severe cases of pollen infection do require medical attention.

BoxBuxus sempervirens. A common species found in bonsai collections is one to handle with caution as it is poisonous to humans. The leaves produce an alkaloid buxine which causes nausea, vomiting and diarrhoea and respiratory paralysis in humans and livestock. Contact with skin can cause irritable rashes and when pruning the clippings should be handled with care.

Cherry (Wild) – Prunus Spp. Wild Cherry trees produce fruit that are reddish black in the summer, which can be consumed. However, the wild cherry twigs and leaves contain the chemical prunasin, a cyanide that when ingested, can be fatal. Prunasin breakdown and cyanide release occurs when the tree becomes stressed and an indication of this is when the leaves begin to wilt.

Chestnut (European horse) – Aesculus hippocastanum. As described above.

CotoneasterCotoneaster Spp. Are grown as bonsai mainly for their display of coloured berries ranging from bright orange to red to purple. This species is said to be a high risk in the toxicity range, because their leaves, berries and flowers all contain cyanogenic glycosides. These toxins if ingested are converted to cyanide during digestion causing serious effect on the heart, liver, kidney and brain. For children the risk is higher than in adults, although much depends on the amount consumed.

CitrusCitrus Spp. Citrus oil is a concentrate of the fruit produced by the tree and also a protective barrier found on the leaves, which can be activated by a gentle rubbing with the fingers. The scent of the oil is pleasant but the taste is bitter, leaving a nasty after taste due to Coumarin a fragrant organic chemical compound in the benzopyrone class. Although citrus oil is not harmful to humans, felines are more susceptible to citrus poisoning, which can result in diarrhoea, vomiting, liver damage or even death.

Douglas FirPseudotsuga menziesii. A native of north America has smooth grey bark when young that are covered with numerous resin blisters, which should not be ingested. The leaves needle like in appearance have two whitish stomatal bands on their underside, that are pores to allow the exchange of gas. If the leaves are damaged they emit a sweet fruity-resinous scent. Ingesting needles can result in vomiting, anorexia, abdominal pain, and lethargy. Other trees with similar attributes are: the Balsam Fir Abies balsamea, Blue Spruce Picea pungens, Red Spruce Picea rubens, White Spruce Picea glauca, Scots Pine Pinus sylvestris and Red Pine Pinus resinosa.    

DogwoodCornus Spp. A genus comprising of approximately 60 different varieties known for their brilliant floral displays in spring time. The fruits of many dogwood varieties are rather tart and unpalatable due to the amount of Tannins, but can be consumed if cooked. However, fruit of the dogwood in the sub-genus Swida are toxic and should be avoided. Dogwoods are prone to attack by insects and fungal disease for example. Botryosphaeria Canker a dark yellowish pitch that oozes from dogwoods and Phytophthora a reddish orange sap oozing from the tree as a result of destroyed tissue. Dogwoods infected with this disease should be kept away from pets, children and other plants.

Dieffenbachia – Family Araceae. A native from Mexico, West Indies and Argentina is widely cultivated as an ornamental houseplant and although not considered by some traditionalists as bonsai material, it is found in some collections. Dieffenbachia is poisonous, it contains Raphides needle-shaped crystals of calcium oxalate crystals and if the leaf or its residue is ingested it causes a burning sensation and erythema a redness of the skin or mucous membranes, caused by increased blood flow. Dieffenbachia can cause other symptoms including numbness, oral irritation and localized swelling.

ElderSambucus racemosa. Elder is cited as a poisonous plant because the bark contains calcium oxalate crystals and the leaves and unripe fruits and seeds cyanoglycoside sambunigrin. But, ripened fruit when subjected to a cooking process reduces the toxins. Elder suffers from Hyphodontia sambuci or Elder Whitewash a basidiomycete fungal pathogen forming a thin white, pruinose (flour-like dusting) on the limbs and branches. The pathogen should be avoided as the spores are easily carried by a gentle breeze.

ElmUlmus. The elm has no toxins to speak of that are a danger to humans or domestic pets but its seeds, leaves and bark should not be ingested as a precaution. Because it is possible that the tree may be infected by Ascomycetes a pathogen relatively common to this species. Ascomycetes not only infest and destroy, they also produce secondary metabolites that are poisonous.

Eucalyptus – Family Myrtaceae. The leaves of this tree contain an oil that if treated and diluted can be safe for adult humans. But untreated oil is extremely toxic and ingesting a small amount (3.5 mL) can have fatal results. Symptoms of eucalyptus poisoning may include stomach pain, a burning sensation, dizziness, muscle weakness, small eye pupils, suffocation, nausea, vomiting, and diarrhoea.

Ficus – Family Moraceae. Is a genus of approximately 850 species that include trees, shrubs and vines collectively known as fig trees. Common species used in bonsai Ficus microcarpa and Ficus benjamina are quite popular especially as a beginners tree. However, they are poisonous due to the milky white sap containing Furocoumarins psoralens and ficin that oozes out when pruned. This sap causes Dermatitis and allergic reactions for example, itching of eyes, coughing and wheezing, skin irritation with redness and stinging.

Forsythia – Family Oleaceae (olive family) is also a popular choice in bonsai and there are eleven species predominately native to Asia. The species Forsythia suspensa is considered a major herb used in Chinese medicinal practices as it is non-toxic. But for safety reasons, one should not consume any part of the plant that is not edible.

Firethorn Family Rosaceae. A large shrub with sharp thorns related to the Cotoneaster (Cotoneaster is thornless). This a popular choice for bonsai due to its bright red and orange fruit that are toxic. The seeds of the berries contain cyanogenic glycosides as do almonds, apples, cherries and plums that can cause gastro-intestinal problems when ingested raw. They are only edible if crushed and washed under running water.

In toxic bonsai part II we continue the discussion on species ‘G’ to ‘M’ until then BW, N.