Not all but some tree and plants are poisonous to pets, animals and humans, that produce toxins or contain poison. Poisonous plants found in India also includes Rosary pea, Datura and madar, a divine flower with list of medical uses and offered to Lord Shiva.
The suicide tree is native to India and other parts of Asia, Mostly found around the coastal salt swamps and in marshy areas and known to contain toxins which are dangerous for human.
Strychnine tree is also native to India and to southeast Asia, known as poison nut tree and source of the highly poisonous seeds but at the same time used to promoted within herbal medicine.
Marking nut tree or varnish tree found in India from Himalayas to Coast of Tamil Nadu. The deciduous tree is closely related cashew and some parts of tree are used in Ayurvedic for medicine but the black fruit is toxic.
Yellow oleander is another most poisonous plant found in India, though cultivated widely as an ornamental tree. The bright yellow, white and orange flowers are used for worshiping Lord Shiva in India and a divine temple flower.
The West Indian laurel also knonw as Alexandrian laurel is widely used for producing a very hard and durable wood but the fruits and leaves contain compounds said to be poisonous to fish. Calophyllum inophyllum are best known as an ornamental plant for fragrant white flowers and decorative leaves.
Sea poison tree is grown for decorative in some parts of India but native to mangrove habitats. All parts of the tree are poisonous to human and the seed powder are also used to kill fish.
Castor oil plant widespread throughout India and source of castor oil, highly poisonous seeds and one of the most poisonous common plant found in the world. India is the largest producers of castor oil seed followed by China and Mozambique.
Saptaparni is the state tree of West Bengal and known as Saptaparni, Flowers bloom in the month of October and are very fragrant similar to the Cestrum nocturnum flowers. Alstonia scholaris is an evergreen tree and said that this tree is causing seasonal fevers as well as not good for the people with asthma.