Plants are beneficial to us as humans because they add oxygen to the air, provide us with food and are enjoyable to look at. Some plants cause discomfort to some people by allergic reactions. Although not everyone is allergic to these plants, there are some who experience a rash or intense itching. Look for these types of plants before you do landscaping in your yard or venture out into the woods.
Poison ivy is one of the most common skin irritants in the plant world. Poison ivy grows close to the ground and also climbs up anything tall such as trees, houses and poles. Poison ivy is easily recognisable by its three shiny leaves. The sap on poison ivy leaves is what causes the reaction. This sap can transfer from the leaves to other objects as well as human skin. Sap will remain on objects such as backpacks and sleeping bags for up to one year and could cause an itchy rash, even if you have not been near the plant itself.
Exposure to stinging nettles makes you feel almost as if several bees are stinging you all at one time. You will first experience a burning sensation, with a rash to follow. There are toxins found in stinging nettles that cause the itching and rash reaction when they come in contact with human skin. These toxins are formic acid, histamine, acetylcholine and 5-hydroxytryptamine. The nettles grow to three to four feet tall. Stinging nettles grow from rhizomes and spread quickly if not dug up and taken care of promptly.
Poison oak is similar to poison ivy except that the leaves are shaped like oak leaves and are a little fuzzy. Poison oak vines are found only in North America, and mainly on the west coast. Be careful getting rid of poison oak. Even after the plant is dead, it still contains the toxins that cause the itchy rash.
Poison sumac is a tree that causes the same itchy rash as poison oak and ivy. The leaves of poison sumac contain about 13 leaflets. Poison sumac is beautiful in the fall when the leaves turn a brilliant red colour, but it is dangerous all year 'round. Poison sumac contains urushiol, which is what causes a reaction when it comes in contact with the skin.