Poisonous Plant plant, plant product or its derivatives which produce deleterious effects on human and other animals' body or cause their death when taken in relatively smaller quantities. Poisonous plants, however, do not include those edible plants which are toxic in the fresh state, but lose their toxicity on being dried or cooked.
Poisonous plants have been the subject of practical lore since ancient times. Their systematic study, in terms of modern science, is often considered to have begun during the 16th century, when the Swiss physician and alchemist Paracelsus first studied the chemical nature of poisons. However, Indigenous Systems of Medicine in this subcontinent had studied and recorded detail accounts of poisonous plants way back in 1500 BC.
Table Some poisonous plant in Bangladesh Local name Scientific name Poisonous parts Poisonous effects Kunch Abrus precatorius Seeds, roots Abortifacient, emetic, cathartic, cattle poison. Ata Annona squamosa Roots, seeds Roots are drastic purgative, seeds are strong eye irritant. Shialkanta Argemone mexicana Seeds, latex Seeds cause severe dropsy, vomiting and diarrhoea; latex is irritant. Hijal Barringtonia acutangula Fruits Fruit causes severe vomiting Akanda Calotropis gigantea Latex, leaves Latex is violent purgative, abortifacient, infanticide, leaves are homicidal poison. Bhanga Canabis sativa Latex, leaf, flower Loose motion Papaya Carica papaya Latex of young fruit Latex is intestinal irritant, induces abortion. Makal Citrullus colocynthis Fruits Powerful hydragogue and cathartic. Swarnalata Cuscuta reflexa Whole plant Antifertility, decoction causes nausea, vomiting and abortion. Dhutra Datura innoxia Seeds Dryness of mouth, delirium, fever, convulsion Dundul Luffa cylindrica Fruits Fruit juice of wild plant, causes severe purgation. Ghora Neem Melia sempervirens Fruits Fruits produce nausea-spasm and choleric symptoms. Rakta Karobi Nerium indicum All parts Cause death on ingestion; roots cause abortion on local application. Chita Plumbago zeylanica Whole plant Extract; causes paralysis Palik Ranunculus scleratus Whole plant Highly acrid, causes violent irritation; paralysis and convulsion, slows respiration, depresses heart's action. Kuchila Strychnos nuxvomica Seed Respiratory failure, nausea, muscle twitching. Tagor Tabernaemontana divaricata Fruits, seeds Fruits are deadly poisonous; seeds are narcotic, poisonous, produce delirium. Helde Karobi Antamul Thevetia peruviana Tylophora indica Bark, seeds, latexLeaves, roots Cause serious depression, paralysis and death. Plant juice causes vomiting, unconsciousness, death.
A particular plant acquires the poisonous property when it accumulates some special types of chemical substances like alkaloids, glycosides, toxalbumins and the like in substantial quantities in its cells. However, when used in regulated doses, most of these apparently poisonous plants may also produce beneficial therapeutic effects due to the presence of the same chemical substances. Thus it is very difficult to draw a distinct boundary between the poisonous and the medicinal plants as most of these plants qualify for both the categories for the above reasons. Some of them are, of course, drastically poisonous, ie, they cause death immediately after administration. They are often used for suicidal and homicidal purposes. Many of them are also used for criminal abortions and for other similar purposes.
An estimated 5,000 species of phanerogamous plants grow in Bangladesh, about 500 of which are regarded as medicinal plants as they possess therapeutic properties. Some of these medicinal plants (about 50) are also classified as poisonous plants as they produce toxic effects on the animal system, if they are not used carefully or in regulated amount. A number of such poisonous plants of Bangladesh are listed in the table.
However, almost all of these plants are also regarded as medicinal plants as they possess medicinal properties and therapeutic values. Indiscriminate and irresponsible use of any medicinal plant may become dangerous since all medicinal plants possess some degree of toxicity. [Abdul Ghani and Mostafa Kamal Pasha]
See also herbal medicine.