Info about poison rash
Poison oak also forms dense thickets in chaparral and coastal sage scrub, particularly in central and northern California. The poison oak rash usually starts as small red bumps, and later develops blisters of variable size. Your health care provider can usually make this diagnosis by the appearance of the rash alone. He or she will ask you some questions about the reaction, your symptoms, and your medical history. North Americans and English gardeners are not the only ones exposed to Toxicodendron dermatitis. In his monograph of poison oak and poison ivy, Gillis (1971) lists four native species of Toxicodendron in North America, including seven subspecies of poison ivy. He also lists three species in Malaysia and China, including two subspecies of poison ivy, one in China and one in Japan.