Cashew Family (Anacardiaceae)

Various species in the cashew family are native to North America. One of the more familiar groups includes species of vines and shrubs in the genus Toxicodendron, many of which contain a toxic oil that causes a contact dermatitis in people exposed to crushed foliage, stems, or roots. It appears that some people develop an increased sensitivity to this toxic oil with increased exposure. Many people appear to not have been initially affected by contact with poison ivy and its relatives, but subsequent exposures then elicited sensitive responses. In contrast, others appear to progressively obtain an immunity to the toxic oil of these plants. Especially severe poisoning can be caused if smoke from the burning of Toxicodendron biomass is inadvertently inhaled—human deaths have been caused by this type of exposure resulting from severe blistering of the pharynx and lungs. The most widespread species is known as poison ivy (T. radicans, sometimes known as Rhus radicans), a plant with distinctive, shiny, compound leaves with three leaflets, and shiny, white berries. Poison ivy can grow as a perennial ground cover or as a vine that grows up trees. Other toxic species include poison oak (T. toxicodendron) and poison or swamp sumac (T. vernix), both of which are shrubs. The Florida poison tree or poisonwood (Metopium toxiferum) grows in southern Florida.

Various species of sumac (Rhus spp.) occur as shrubs in North America. One of the more familiar species is the staghorn sumac (Rhus typhina), the fruits of which are sometimes collected and used to prepare a lemonade-like drink. Other widespread species are the shining or mountain sumac (Rhus copallina), smooth or scarlet sumac (R. glabra), fragrant sumac (R. aromatica), and ill-scented sumac or skunkbush (R. trilobata).

The wild smoke-tree (Cotinus obovatus) occurs in the southeastern United States and is sometimes grown as an ornamental shrub.