Hi welcome to Taiga Bonzai, we continue our journey through the alphabet starting with the letter ‘R’.

Introduction – all trees and shrubs have some form of defence, some highly toxic and dangerous to domestic animals and humans. Whilst others are not considered harmful. Yet some whom work with these plants do not take adequate precautions, hence with negative results.

Rhododendron – Spp. 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 Rhododendron 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 Pea – Abrus 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. This 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.

Rowan – Sorbus 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 with orange to red berries.

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.

Snowberry – Symphoricarpos 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 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 tree – Euonymus 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. However, the fruits are poisonous, 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.

Spurges – Euphorbia Spp. family Euphorbiaceae. A genus with 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.

 Tamarac – Larix laricina. family Pinaceae. Known as the black, eastern, red and American larch, is native to north America and Canada. This species is both 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.

Titoki – Alectryon 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 it’s fruit are a pink to 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, it contains tannins and cyanide producing poisons in the bark, leaves and fruit. If ingested can cause; vomiting, gastroenteritis, diarrhoea, delirium, kidney failure and at worse fatality.

Tea tree (Chinese) – Camellia sinensis family Theaceae. This 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. Causing; dizziness, headaches, palpitations, indigestion, constipation and insomnia. Moreover, excessive intake or over indulgence can be harmful to pregnant women.

In the next article on this subject ‘toxicity’ we continue with the letter ‘U’, until next time, BW, Nik.