Ever since I saw a small child munching on a leaf of philodendron while her mother went on nonchalantly chatting to a friend, I have been concerned by the general lack of awareness of the poisonous properties of many plants. Large sums are spent educating people on the dangers of drugs and poisons in the home, but ignorance still exists to the dangers that lurk in the garden.
Most of the poisonous plants are angiosperms or flowering plants. There are approximately 300 families of angiosperms, comprising about 200,000 species. Fortunately only a very small percentage are poisonous. Plants may be poisonous if eaten on upon contact, produce photosensitization or produce airborne allergies.
There are many chemical substances that produce plant poisons or phytotoxins. These include alkaloids, polypeptides, amines, glycosides, oxalates, resins and a large group of miscellaneous compounds whose structures are still to be determined.
In almost any garden one would find plants with these poisonous properties. Let us look at just a few.
Cotoneasters, popular because of their brightly colored berries, yield prussic acid. However, they appear to be poisonous only when grown in climates with severe winter snow.
Poisonings have been recorded overseas after people have chewed the bark or succulent fruits of daphne species. Daphne odora Rubra is commonly grown for the fragrant blooms and attractive evergreen bushes.
Delphiniums and larkspurs contain alkaloids, including delphine, which are extremely poisonous. The foxglove, Digitalis purpurea, contains about 12 cardiac glycosides, the most important of which is digitoxin. Although used for medical purposes, an overdose can be fatal.
Two climbers, Gelsemium sempervirens and Wisteria sinensis, are poisonous, all parts being toxic.
Even hydrangeas are listed as poisonous and records show that adults and children in one family suffered gastroenteritis after eating a salad containing hydrangea buds.
The blackberries of the hedge plant, Ligustrum lucidum (privet), have been suspected of poisoning children but is believed it would take a significant number of berries to produce symptoms of diarrhea in a child.
Children are reported to have died after eating six to eight of the ripe fruits from the lovely Melia azedarach, the white cedar, and two other popular garden trees, Robinia pseudoacacia and Laburnum vossii, are known to produce nervous symptoms, vomiting spasms, and convulsions if eaten.
Probably the most dangerous garden to-grow plant, all parts of which are poisonous.
Fortunately, Ricinus communis, the castor-oil plant, is now rarely planted in home gardens. The ricin in this plant is quite lethal, and two to eight seeds can kill when eaten.
Toxicodendron succedaneum, the scarlet rhus, can cause severe dermatitis and facial swelling. However, it has been found that sensitivity may take many years to develop.
Even our food plants have their problems. The leaf blade of rhubarb, Rheum rhapomticum, is extremely poisonous and can cause nausea, vomiting and diarrhea, eaten raw. The leaf stalk is edible when cooked. The green sprouts, green tubers, stems and leaves of the common potato, Solanum tuberosum, can produce gastroenteritis, loss of sensation, apathy and even paralysis if eaten.
Fruit trees, too, are not without their poisonous properties. The fresh leaves of the quince, Cydonia oblonga, have been found to produce a small percentage of prussic acid and the seeds are also cyanogenetic, as are the leaves and seeds of the loquat, Eriobotrya japonica. The seeds of the apple, Malus sylvestris, yield this acid in sufficient quantities to be poisonous if eaten in large amounts, and the kernels of Prunus amygdalus, the bitter almond, contain potentially dangerous quantities of glycosides.
Seeds of the cherry, Prunus avium, are reported to be cyanogenetic, but no cases of poisonings have been recorded. However, a woman who ate 20 kernels of the apricot, Prunus mume, showed symptoms of poisoning but recovered rapidly once the stomach was emptied. The bark, leaves, flowers and kernels of Prunus persica, the peach, yield prussic acid, and a number of cases of poisonings have been recorded in Australia.
Bulbs and herbaceous perennials also have hidden dangers. The belladonna lily contains atropine and children and animals have been poisoned by eating the fruit. Ingestion of arum lily, Zantedeschia aethiopica, can cause irritation of the mouth and stomach lining, accompanied by violent pain, and ingestion of lily of the valley, Convallaria majalis, can produce nausea, dizziness and irregular heart action. The sap and bulb of daffodils, Narcissus pseudo-narcissus, are quite toxic. Symptoms of poisoning are vomiting and gastroenteritis.
Garden weeds, while they will not have the same attraction to small children as decorative plants, can still be placed in the poisonous category. Urtica species, nettles, can produce skin irritation and pain. The foliage and fruit of Solanum nigrum, blackberry nightshade, can produce symptoms from gastroenteritis to paralysis if eaten even in its unripe stage, and the latex from Euphorbia peplus, petty spurge, can cause blistering to the mouth and stomach mucosa.
Finally let us look at indoor plants, for it was an indoor plant that drew my attention to this problem. All parts of dieffenbachia, philodendron and monstera species are extremely poisonous and ingestion can cause irritation, burning of the mucous membrane, and copious watering of the mouth, accompanied by severe swelling.
So what can be done about this? Obviously we cannot remove all the offending plants from gardens, so the public must be made aware of the dangers. More publications on these plants must be made available.
People with small children should avoid poisonous plants when establishing a garden, and these plants should be omitted from school and kindergarten gardens, and parks. Children should be encouraged never to eat berries or seeds of any kind.
Nature protects children to a certain extent by making most poisonous plants vile-tasting, but if poisoning is suspected it is essential to get medical attention immediately. If possible take a piece of plant for identification.
If the mouth is burnt or blistered, DO NOT induce vomiting but give large quantities of milk to drink. Vomiting can be induced if no burning occurs, and follow this with large quantities of milk.