Hi welcome to Taiga Bonzai, in this article we continue our discussion on a selection of tree and shrub species used in bonsai that have defence capabilities.

Introduction – as stated earlier horticultural enthusiasts be they bonsai enthusiasts or keepers of exotic plants, have various species in their collections. More often than not very little research is undertaken in understanding of what a particular plant has in it’s defence.

All plants are able to produce toxins that have the power to incapacitate all fauna including humans, but as to the level remains to be seen. We have mentioned alphabetically a few tree examples from ‘A’ to ‘E’, we continue with the letter ‘F’ onwards.

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.

Gelsemium – family Gelsemiaceae common name Carolina jessamine is a twining vine, native to subtropical and tropical America: Honduras, Guatemala, Belize, Mexico, and south eastern and south-central United States All parts are poisonous, causing nausea and vomiting. It is possible to become ill from ingesting honey made from jessamine nectar.

Gloriosa superba – family Colchicaceae known as the flame lily or climbing lily is highly toxic due to colchicine contained within the plant. The early signs of toxicity develop within two hours of ingestion and include vomiting, diarrhoea, numbness and severe effects on the throat leading to dehydration. It can lead to respiratory, hepatic and renal failure individually and multiorgan failure within 24 to 72 h.

Grevillea Spp – in the family Proteaceae is known by other names including silky oak and spider flower. Grevillea robusta is a fast growing evergreen tree with a single main trunk, growing to 5–40 m (20–100 ft) tall. The bark is dark grey and furrowed and the leaves are fern-like. These are shed prior to flowering. The flowers and fruit contain toxic hydrogen cyanide and tridecylresorcinol responsible for contact dermatitis.

Hedera – family Araliaceae common name Ivy including the rampant colourful Virginia creeper are toxic. All species of Hedera contain irritant and allergenic compounds in all plant parts. They are especially concentrated in young leaves and fruit and remain throughout the seasons. Contact dermatitis can be caused at any time.

Helleborus niger – family Ranunculaceae common name Christmas rose is also toxic. It Contains protoanemonin or ranunculin, which has an acrid taste and can cause burning of the eyes, mouth, and throat, oral ulceration, gastroenteritis, and hematemesis. Hellebore poisoning is rare, but it does occur. These plants are usually left alone by animals such as deer and rabbits because the leaves of the plant produce poisonous alkaloids.

Hippomane mancinella – family Euphorbiaceae known in Spanish as the ‘manzanilla de la muerte ‘apple of death found in the Caribbean region. All parts of this tree, including the fruit, contain Toxic phorbol esters typical of the Euphorbiaceae family.

It contains deoxy, hydroxyphorbol, gamma, alpha-oxide, hippomanins, mancinellin, sapogenin and phloracetophenone. Dimethylether is present in the leaves and physostigmine in the fruit. This tree species according to the Guinness book of records is listed as the world’s most dangerous tree. Hence it is doubtful anyone would want to cultivate it, knowing the consequences that await.

Indian Pea – Lathyrus 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.

Jacobaea vulgaris – family Asteraceae, commonly known as ‘ragwort’ contains many different alkaloids, including jacobine, jaconine, jacozine, otosenine, retrorsine, seneciphylline, senecionine and senkirkine. This plant is poisonous to livestock including equines and cattle, hence there is concern for people who keep such animals.

Jacobaea vulgaris is also theoretically poisonous to humans, although poisoning is unlikely as it is distasteful and not used as a food source. Nonetheless, some sensitive individuals can develop an allergic skin reaction after handling the plant. Because it contains sesquiterpine lactones, which differ from the pyrrolizidine alkaloids responsible for the toxic effects, that can cause compositae dermatitis.

Juniper – Juniperus sabina also known as the ‘Savin’ Juniper is a popular conifer used in bonsai. In Calgary Alberta Canada it’s popularity is such that it is widely cultivated. However, Savin Juniper is known to be toxic and potentially deadly poisonous if taken in large enough quantities. For example, those who make juniper syrup using Savin Juniper without realizing the potential toxicity.

According to the article by Papavassiliou published in the French journal Société de Médecine Légale in 1937, indicates that in two cases of poisoning, oil of Savin was able to cross the placental barrier. Jacobs and Madari (2004) the oil of Savin (also know as Sabine) was found in the viscera of the foetus demonstrating the ability of the oil to cross the placental barrier.

Savin oil contains sabinene, sabinyl acetate and sabinol, compounds that are structurally related to thujane, thujol, and thujone. The latter are well known for their toxic effects and are found in infamous plants such as Tansy (Tanacetum vulgare) and Wormwood (Artemisia absinthium).

Savin oil can cause irritation of the mucus lining of the intestines, congestion of abdominal organs, congestion of the kidneys leading to haematuria (blood in the urine), menorrhagia (heavy menstrual bleeding) and abortion.

Jacaranda – is a genus of 49 species of flowering plants in the family Bignoniaceae, native to tropical and subtropical regions of the Americas, Africa and cultivated around the world.

The species are shrubs to large trees ranging in size from 20 to 30m (66 to 98 ft) tall. The leaves are bipinnate in most species, pinnate or simple in a few species. The flowers are produced in conspicuous large panicles, each flower with a five-lobed blue to purple-blue corolla; a few species have white flowers.

While Jacaranda flowers are not considered toxic to humans, they can cause mild gastrointestinal upset if ingested. Jacaranda trees are a stunning addition to any landscape or as bonsai, with their beautiful flowers and graceful form.

In these articles on ‘toxicity’ part III we continue the discussion on species ‘K’ onwards, until next time, BW, Nik.

Hi welcome to Taiga Bonzai, we continue our journey through the alphabet discussing the toxicity of trees and shrubs, some of which are used in bonsai horticulture.

Introduction – some of the species mentioned here are endemic to tropical and sub-tropical regions, others are found in the northern hemisphere.

Umbrella tree – Schefflera 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. Leaf consumption can cause mouth tingling and numbness, vomiting and abdominal pain and sap when in contact with skin can cause irritation and rash.

Viburnum – Lantana. 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.

It’s 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. These 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.

Viburnum – Opulus. 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; the 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 creeper – Parthenocissus 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) It 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 cedar – Spp. 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 of plicatic acid and exposure to it 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.

Willow – Salix alba. family Salicaceae. Is a species native to Europe, but is also found in western and central Asia. 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 contains salicylate toxins in the bark that if ingested can cause the following. Ulcers, nausea, vomiting, stomach bleeding, kidney inflammation, tinnitus and skin rash.

Wisteria – Spp. family Fabaceae. Includes various species of climbing vines. (Plants that climb by their shoots) Wisteria brachybotrys, Wisteria brevidentata, Wisteria floribunda, Wisteria frutescens, Wisteria macrostachya, Wisteria sinesis, Wisteria venusta and Wisteria villosa.

These Wisteria types 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.

In the next article on ‘Toxicity’ we conclude our journey through the alphabet with ‘X’, ‘Y’ and ‘Z’. Until next time, BW, Nik.