Dr. Ishrak K. Khafagi
Faculty of Science, Suez Canal University, Ismailia, Egypt
Many poisonous plants are so common and seemingly innocuous that we do not suspect their toxic qualities. A poisonous plant is the â€œone which give rise to a serious departure from normal health, when a certain part of it is eaten by a creature which is susceptible to its effects. Plant poisons are found either in all parts of the plant or concentrated in one or more of them. They vary in amount within a given species according to habitat, weather, type of soil, season or age. Their effects are ruled by the age, size, environmental physical conditions and sensitivity of the affected organism as well as by the quantity ingested. Plant toxic substances are alkaloids (atropine, colchinine, gelsemine, hyoscyamine, and taxine), glycosides including cardiac glycosides (convallamarine, digitalin or oleandrine), cyanogenetic glycosides (amygdalin), saponins (githagin), and other glycosides such as aesculin. Moreover, oxalates (calcium oxalate crystals), phytotoxins (protein molecules such as ricin), resinoids (andromedotoxin) as well as goitrogens produced by some members of the genus Brassica are the groups of toxic principles found in poisonous plants. Most common toxic plant species grown in Egypt are Ricinus communis L. (Euphorbiaceae), Datura stramonium L.,Hyoscyamus niger L. (Solanacea), Nerium oleander L.(Apocynaceae), Peganum harmala L. (Zygophyllacea), Senecio desfontainei Druce (Compositae) and lantana camara L.