Toxicodendron in the context of Lacquer

Toxicodendron vernicifluum (formerly Rhus verniciflua), also known by the common name Chinese lacquer tree, is an Asian tree species of genus Toxicodendron native to China and the Indian subcontinent, and cultivated in regions of China, Japan and Korea. Other common names include poison sumac, Japanese lacquer tree, Japanese sumac, and varnish tree. The trees are cultivated and tapped for their toxic sap, which is used as a highly durable lacquer to make Chinese, Japanese, and Korean lacquerware.

The trees grow up to 20 metres tall with large leaves, each containing from 7 to 19 leaflets (most often 11–13). The sap contains the allergenic compound urushiol, which gets its name from this species' Japanese name urushi (urushi (漆)); "urushi" is also used in English as a collective term for all kinds of Asian lacquerware made from the sap of this and related Asian tree species, as opposed to European "lacquer" or Japanning made from other materials. Urushiol is also the oil found in poison ivy and poison oak that causes a rash.

Urushiol /ʊˈruːʃi.ɒl/ is an oily mixture of organic compounds with allergenic and sensitizing properties found in plants of the family Anacardiaceae, especially Toxicodendron spp. (e.g., poison oak, Chinese lacquer tree, poison ivy, poison sumac), Comocladia spp. (maidenplums), Metopium spp. (poisonwood), and also in parts of the mango tree and the fruit of the cashew tree.

In most individuals, urushiol causes an allergic skin rash on contact, known as urushiol-induced contact dermatitis.

Poison ivy is a type of allergenic plant in the genus Toxicodendron native to Asia and North America. Formerly considered a single species, Toxicodendron radicans, poison ivies are now generally treated as a complex of three separate species: T. radicans, T. rydbergii, and T. orientale. They are variable in appearance and habit, and despite its common name, it is not a true ivy (i.e., Hedera), but rather a member of the cashew and pistachio family (Anacardiaceae).

Though T. radicans is commonly eaten by many animals and the seeds are consumed by birds, poison ivy is most often thought of as an unwelcome weed. It is well known for causing urushiol-induced contact dermatitis, an itchy, irritating, and sometimes painful rash, in most people who touch them. The rash is caused by urushiol, a clear liquid compound in the plant's sap.

Poison oak refers to two plant species in the genus Toxicodendron, both of which can cause skin irritation:

• Toxicodendron diversilobum or Pacific poison oak, found in western North America
• Toxicodendron pubescens or Atlantic poison oak, found in southeastern North America

Urushiol-induced contact dermatitis (also called Toxicodendron dermatitis or Rhus dermatitis) is a type of allergic contact dermatitis caused by the oil urushiol found in various plants, most notably sumac family species of the genus Toxicodendron: poison ivy, poison oak, poison sumac, and the Chinese lacquer tree. The name is derived from the Japanese word for the sap of the Chinese lacquer tree, urushi. Other plants in the sumac family (including mango, pistachio, the Burmese lacquer tree, the India marking nut tree, and the cashew) also contain urushiol, as do unrelated plants such as Ginkgo biloba.

As is the case with all contact dermatitis, urushiol-induced allergic rashes are a Type IV hypersensitivity reaction, also known as delayed-type hypersensitivity. Symptoms include itching, inflammation, oozing, and, in severe cases, a burning sensation. Additionally, smoke from burning plant matter may be toxic.

Toxicodendron diversilobum (syn. Rhus diversiloba), commonly named Pacific poison oak or western poison oak, is a woody vine or shrub in the sumac family, Anacardiaceae.

It is widely distributed in western North America, inhabiting conifer and mixed broadleaf forests, woodlands, grasslands, and chaparral biomes. Peak flowering occurs in May. Like other members of the genus Toxicodendron, T. diversilobum causes itching and allergic rashes in most people after contact by touch or smoke inhalation. Despite its name, it is not closely related to oaks, nor is it a true tree.

Toxicodendron succedaneum, the wax tree, Japanese Hazenoki tree (Sumac or wax tree), sơn in Vietnamese or charão in Portuguese, is a flowering plant species in the genus Toxicodendron found in Asia, although it has been planted elsewhere, most notably Australia and New Zealand. It is a large shrub or tree, up to 8 m tall, somewhat similar to a sumac tree. Because of its beautiful autumn foliage, it has been planted outside Asia as an ornamental plant, often by gardeners who were apparently unaware of the dangers of allergic reactions. It is now officially classified as a noxious weed in Australia and New Zealand. It is one of the city tree symbols of Kurume, Fukuoka, Japan.

The larvae of the moths Eteoryctis deversa, Caloptilia aurifasciata, Caloptilia protiella, Caloptilia rhois, and Callidrepana patrana feed on T. succedaneum.

Toxicodendron rydbergii, the western poison ivy, is a species of Toxicodendron in the cashew family native to North America. As a poison ivy, it can cause urushiol-induced contact dermatitis.

Toxicodendron orientale (Asian poison ivy) is an East Asian flowering plant in the genus Toxicodendron. It is a poison ivy, which can cause urushiol-induced contact dermatitis.