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 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 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.
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. 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.
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 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 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) 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 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. 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.
Willow – Salix 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.
Wisteria – Spp. 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.
Xanthorhiza – simplicissima. 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.
Xanthoceras – sorbifolium. 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.
Yew – Taxus 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.
Zelkova – Serrata 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.