Poison sumac does not have thorns. There are numerous species of sumac, both poisonous and non-poisonous, growing in North America, and none of the species posses thorns.
Poison sumac grows throughout North America in wet, swampy areas. Contact with poison sumac results in contact dermatitis and inflammation; it also causes itching and blisters. Poison sumac can grow up to 18 feet tall, but usually is found in shrub form, close to the ground.
Poisonous sumac comes in two varieties: Chinese sumac and Texan sumac. Non-poisonous sumac comes in many varieties, can grow in tree form and reaches heights of 25 feet if grown in well-lit, well-drained areas.