Tree pollens generally do not cross-react among themselves. Therefore, if you are allergic to one tree pollen, you are not necessarily allergic to another. Two types of trees are exempt from this rule: 1) the family that contains beech, oak, and birch, and 2) the one that contains cedar and juniper. If you are allergic to one of these trees, you will likely experience symptoms in at least one tree in the same family.