Hay fever is actually an allergy to what substance, vital to plant reproduction?

Did you ever hear of hay fever? Its not really a fever at all. Its an allergy to plant pollens. People with this type of allergy have symptoms such as watery eyes, sneezing, and a runny nose. A common cause of hay fever is the pollen of ragweed. Many people are also allergic to poison ivy Figure below . Skin contact with poison ivy leads to an itchy rash in people who are allergic to the plant.