By CATHERINE MASTERS
Queries about plants make up about 10 per cent of all calls to the National Poisons Centre at Otago University in Dunedin.
Topping the list is the arum lily, which is common throughout New Zealand and causes a burning sensation if eaten.
Medical toxicologist Dr Michael Beasley says plants have a range of toxins.
Some are toxic to the gut, leading to vomiting and diarrhoea - or a sore mouth, which is where the arum lily comes in.
"That has oxalates in it which can cause an inflammatory condition of the mouth. Calcium treatment such as milk is very useful," says Dr Beasley.
A few plants, such as foxgloves, have a digitalis-like action which can be toxic to the heart.
"Probably the most common form of poisoning is the atropine-like compounds (belladonna) and people can get dilated pupils, blurred vision. They can get hot and dry, confused, that sort of thing."
There is an antidote for this but it is used only as a last resort. Patients can become aggressive and Dr Beasley says they should be nursed in a quiet, dark room with mild tranquillisers.
The pumping of stomachs is not performed often, not even for hemlock, and is recommended only if the patient is in hospital within an hour and already pretty sick.
The standard treatment is to give charcoal, which binds the toxins and stops them from being absorbed.
Parents should not give charcoal without medical advice.
Dr Beasley says first aid treatment is fairly limited for parents and it is no longer recommended to make poisoned children vomit.
"Really the best thing is to call a doctor or the poison centre," he says.
Children can be given a small amount of milk or water but not too much.
"In the old days people used to think 'Oh, I'll give lots and lots of fluids to dilute the poison,' thinking 'Oh well, that will decrease the concentration and therefore you won't absorb as much.'
"But the other thing is, if you give too much it spreads the poison over a bigger surface area. A bit of a trade-off goes on. If you give too much liquid it might also make them vomit."
* The poisons centre has a 24-hour telephone number: (03) 474-7000.
Banish these plants to keep youngsters safe
Some plants should not be grown or tolerated in preschool centres. Ones which are harmful if swallowed include:
* Angel's trumpet. Found in the North Island and warmest parts of the South Island.
* Arums and arum lily.
* Bittersweet. Found mainly in the South Island and lower North Island.
* Death cap and fly agaric fungi.
* Jerusalem cherry.
* Laburnum. Found mainly in the South Island and southern half of the North Island.
* Lantana. Warmer parts of the North Island and northern parts of the South Island.
* Lily of the valley. Mainly South Island.
* Persian lilac or white cedar.
* Potato (all green parts).
* Privet species.
* Queen of the night. Mainly northern North Island.
* Stinking iris.
Plants which are harmful if touched include:
* Stinging nettles.
* Wax tree, or Japanese wax tree. Mainly North Island and northern South Island.
Landcare Research has not included some extremely poisonous plants in this list because they are rare. An example is deadly nightshade, which is often confused with black nightshade. Deadly nightshade is more than 1m tall when mature and has large, bell-shaped, brownish-purple flowers, followed by large, egg-shaped black berries.
By CATHERINE MASTERS