Poisonous Plants in New Zealand- Introduction
This information applies to all parts of New Zealand and replaces the separate lists for the North and South Islands from 1999. Also available is “Safety in Pre-School Centres”, a list of plants that are not recommended to be grown in pre-school centres.
Introduction
Most books on poisonous plants in New Zealand have been designed for farmers and have concentrated on those which are poisonous to stock. Although the information in these books may be relevant, it is not always directly applicable to people. Plant material that may be eaten safely by animals and birds may not necessarily be safe for humans. This checklist was prepared at the request of childcare workers who wanted guidance on plants which might be harmful if eaten by young children. The lists are not intended to be used for the identification of plants or as a guide for weediness. In addition to the plants listed, a very brief account of poisonous fungi is included at the end of the list of plants that cause poisoning when taken internally. (See the Further information section at the end.)
The following lists contain only those plants which children may be tempted to eat and touch and which are commonly found in and around gardens, parks, and other recreation areas. The first list includes plants that cause harm when eaten. For most species in this list, the main thing is to keep young children from eating the fruits or berries when they are present on the plant. As a general rule, children should be discouraged from eating any new plant material unless guided by an adult. The second and much shorter list includes plants that can cause skin irritation when they are touched, and pre-school children should be supervised when there is a likelihood of contact with such plants. However, many of these only react with skin when there is contact with sap from broken parts of the plant. The third list is of plants with fruits that children may be tempted to eat but which are not poisonous and thus need not cause concern.
Scope of the list
Many potentially poisonous plants are not listed because they are unlikely to be eaten by children, e.g., box (Buxus sempervirens)and its relations such as the now popular Allegheny spurge (Pachysandra terminalis) used for ground cover. Also many plants in the forget-me-not family (Boraginaceae) which have harsh bristly leaves, and bracken or rarauhe (Pteridium esculentum), a traditional Māori kai/food plant which requires cooking to make it edible. Also there are other poisonous but tough-leaved membersof the erica or rhododenron family that are not mentioned in the list because they are not only unattractive to children but are often uncommon, eg. calico bush (Kalmia latifolia) and its close relations. Most gardens in New Zealand contain poisonous plants. Many plants in the following well-known families are poisonous or have poisonous parts: daffodil, snowflake and snowdrop (Amaryllidaceae), oleander (Apocynaceae), arums (Araceae), ivy and five finger (Araliaceae), swan plant, (Asclepiadaceae), heathers and rhododendrons (Ericaceae), lilies (Liliaceae), poppies (Papaveraceae), buttercups and clematis (Ranunculaceae), titoki (Sapindaceae), fox-gloves and snapdragons (Scrophulariaceae), and potatoes and tobacco (Solanaceae). In addition, many species in the large legume or pea family (Fabaceae) and the rose and apple family (Rosaceae) are poisonous to some extent.
Effects of consumption
At some stage of their life cycle many cultivated garden plants and weeds have chemical properties that can cause harm to some people. (The season and stage of growth influence the amount of poisonous substances present in plants.) Do not panic if young children play near such plants. Plants need not be destroyed just because they have poisonous properties. Most of these plants are not tempting for children to eat, at least in potentially harmful amounts; or would pass through the digestive system without causing problems. Examples of the latter are the legumes kowhai and laburnum whose seeds are extremely hard but would only be toxic if ground up first and swallowed. In New Zealand it is inevitable that as children grow up they will be exposed to plants with poisonous properties. To keep things in perspective remember that fatalities are extremely rare and usually a child does not eat enough of a poisonous plant to cause serious illness.
Not everyone who feels ill after eating leaves, flowers, or berries, has been poisoned; it may be simply a failure to digest them properly that causes the stomach-ache. Many plants which are harmless or only slightly toxic can cause stomach upsets if eaten in large quantities; even some edible but very acidic fruits can have this effect. Sometimes the cause is fungi growing on fruit and vegetables that have been kept too long, or in the wrong conditions. People react in different ways to eating poisonous plants, so some people may be relatively unaffected, while some others may become seriously ill.
Plants with edible and poisonous properties
Not all poisonous plants taste unpleasant, so bitter taste is not an indicator of the presence of a poison. It is well known that some plants which are very poisonous when raw can be palatable when cooked. Two of the best examples are the traditional Māori kai/food plants, karaka and taro. Taro belongs to the arum family which contains other edible plants that are used elsewhere, especially in the Pacific islands, but no member of the family can be eaten raw. Certain plants that are widely eaten in small amounts because they are considered to be beneficial to health and well-being, such as comfrey, are unsafe to eat in large amounts. Even such well-known plants as potato and rhubarb have notably toxic properties, and all green parts of the potato (including tubers which have been exposed to light) are poisonous. Similarly, only the stalk of the rhubarb leaf should be eaten. Be careful not to eat food that has come in contact with any part of a very poisonous plant, such as using a poisonous plant as a barbecue stick, because this can also be harmful.
Non poisonous plants
A list of non-poisonous, and often edible, fruiting plants follows the list of poisonous species. Most of these are among our most common garden trees and shrubs. Some plant families have no members in New Zealand likely to cause poisoning. These safe families include: iceplant (Aizoaceae), cabbages (Brassicaceae), chickweed (Caryophyllaceae), fat hen (Chenopodiaceae), stonecrop (Crassulaceae), manuka (Myrtaceae), grasses (Poaceae), and coprosma (Rubiaceae). In addition, the families to which our common catkin-bearing trees belong are unlikely to produce symptoms of poisoning, although the leaves and catkins may taste bitter and eating too many fruits of oaks and beech can cause digestive upsets. These include alders, beeches, birches, sweet chestnuts, oaks, poplars, walnuts, and willows.
Rare poisonous plants
Some plants that are well known overseas as being very poisonous are not dealt with because they are rare in New Zealand and thus very unlikely to be encountered. As already stated, this is not an identification manual so it was felt that inclusion of all such plants would make the list unnecessarily cumbersome. Examples of such excluded plants are: henbane (Hyoscyamus niger), poison ivy (Toxicodendron radicans) and Chinese lacquer tree (T. vernicifluum). An apparent exception is deadly nightshade (Atropa bella-donna) but this very rare plant in New Zealand is only mentioned in the main list because of confusion with the common black nightshade. Of course if one goes to a place where there is a large collection of plants such as a botanic garden, arboretum or some nurseries, many more plants with at least some degree of toxicity in their tissues must be expected.
Warning: If a child is displaying serious symptoms of poisoning, treat as an emergency and dial 111 for an ambulance.
If you suspect a child has ingested parts of a poisonous plant immediately contact the National Poisons Information Centre Urgent Phoneline 24 hours a day seven days a week on
0800 POISON / 0800 764 766
(For nonurgent information, Ph. 03-479 1200 between 9am and 5pm week days only).
W.R. Sykes, June 1991, Revised April 2002
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This information is not intended to be comprehensive or to provide medical advice to you. While all care has been taken to ensure the accuracy of the information, no responsibility is accepted for any actions taken in reliance on it. Specific advice on medical issues should be sought from a health professional.