Only about 5,000 plants of the estimated 400,000 plant species have been scientifically studied in detail. An although we think that a lot has been going on in terms research in the new world, only about 1% of the plants known to traditional cultures have been studied. That is why pristine forests such as the equatorial forests in the Amazonian forest remain and important human heritage. We study plants for many reasons, food, medicine, ornaments, essential oils, aromatics, building, natural products and other uses.
Poisonous plants in pastures, and careless use and handling of highly toxic chemicals can result in tremendous losses in productivity and even life. There are many poisonous plants in UK although some of them not native.
Here is the well known ones;
0. Nightshade (Atropa belladonna)
0. Dumb cane (Dieffenbachia Sp.) it belong to the Araceae family
0. German primula (Primula obconica)
0. Giant hogweed (Heracleum mantegazzianum)
0. Garden rue (Ruta graveolens)
0. Poison Oak (Rhus diversiloba)
0. Poison-ivy (Rhus radicans- it is not a true Ivy but is in the same family as mangoes),
0. Castor Oil plant (Ricinus communis ) is the sole member of the genus Ricinus and is a deadly poison,
0. Manzanillo tree (Rhus striata) it is native to south America
0. Wax tree (Rhus succedanea),
0. Ratsbane (Dichapetalum toxicarium) is a very poisonous tree native to western Africa,
0. Varnish tree (Toxicodendron vernicifluum) ,
0. Poison Sumac tree (Rhus vernix),
0. Water hemlock (Cicuta virosa).
I will now briefly discuss some of these plants. These notes are not to be taken as an authoritative source, always talk to an expert before handling any of these plants. The information contained here maybe inaccurate or out of date. When buying these plants go into details such as knowing the name of the plant, how big it will grows and also remember to ask if it is poisonous. Some plants can affect your skin by merely touching it. Once you have bought, remember to label the plant appropriately to safeguard your family-especially if it one of those common houseplant that you intend to keep in a pot at home.
Water hemlock (Cicuta virosa) and spotted hemlock (Conium maculatum) both native to Britain, are known to contain some of the deadliest poisons in their sap. They belong to same family as carrots, celery and parsley. It is thought that they cause vomiting, delirium and violent convulsions in their victims. The poisons they produce tend to cause death by asphyxiation.
Many houseplants, such as dumb cane (Dieffenbachia) it belongs to the Araceae family and contain calcium oxalate crystals. When chewed, these damage the mouth and throat causing a burning sensation and swelling of the soft tissue. Young children and pets are particularly at risk. The plant commonly called German primula Primula obconica causes an allergic reaction in sensitised people. This plant has started appearing more and more in shops and farms recently. The positive thing is that scientists have produced allergen-free cultivars have been developed in recent years. The garden rue (Ruta graveolens) is known to cause a phototoxic reaction. This can be in form of irritation, pain and blisters result from exposure to plant sap. The reaction is worse if the affected part is exposed to bright sunlight. Giant hogweed (Heracleum mantegazzianum) is a phototoxic plant. Its sap can cause phytophotodermatitis (severe skin inflammations) when the skin is exposed to sunlight or to UV-rays.
Names can cause confusion. Even to taxonomists and experienced gardeners, the visual appearance can lead to misidentification. Several plants have the common name nightshade. Deadly nightshade (Atropa belladonna) has black fruits that have be mistaken for bilberries although they are much larger. The fruits of the more common woody nightshade turn from green, through orange to red. Both are poisonous. Some of these plants have potential for useful medicinal uses, but until they are processed, keep away from them.
Always check with the local gardening association if the plant you want to buy is on the list of known poisonous houseplants before you take it home. You will be surprised to know that most common houseplants are actually listed as poisonous in varying degree-from very poisonous to mildly poisonous. Often these houseplants are not only poisonous to animals such as cats and dogs, but also humans, so please keep your young children away from them.
Lastly, remember some plants are protected and controlled, so make sure you don’t buy a plant imported to this country without a license. You can check the list of plants whose trade is controlled; The Royal Horticultural Society, CITES (an acronym for the Convention on International Trade in Endangered Species of Wild Fauna and Flora), HM Customs and Excise and DEFRA (Department of the Environment, Food & Rural Affairs).
For more information, see these references;
Epic Centre Kew
Royal Horticultural Society