Morning Glory Allergy: What Causes Sneezing?

The culprit originating an allergic response and causing Juan to sneeze when he sniffs the morning glory flower is pollen. Pollen is a fine, powdery substance produced by the male reproductive organs (stamens) of flowering plants. When pollen comes into contact with the mucous membranes of the nose, it can cause an allergic reaction in some individuals, leading to symptoms such as sneezing, itchy or watery eyes, runny nose, and congestion.