Tree Pollen

Tree pollen from a willow tree catkin.

Tree pollen from a willow tree catkin.

Tree pollen is a fine powder that is produced and released by the male flowers on the tree during blooming season. Once the male flowers bloom the wind or insects will carry their pollen to the female flowers to fertilize them. This process is known as pollination and the only method the tree has for reproducing. Regarding fertilization there are two types of trees:

  • Trees that are unisex and have both male and female flowers located on the same tree. Birch and Alder trees are two examples of this type.
  • Trees that have male flowers and female flowers on separate male and female trees. Olive and Holly trees are two examples of this type.

The tree pollens that cause the most allergy symptoms are those that are wind-pollinated. Since wind can be an unreliable guarantee for reproduction, trees mass produce and release their pollen to make sure their female flowers are fertilized. Unfortunately, large amounts of their pollen never reach the female flowers and are carried into the air irritating our eyes, nose, skin, and lungs also known as hay fever.

When is tree pollen season?

Trees are usually the first to pollinate releasing their pollen in the spring. In Southern locations it can be as early as January and in Northern locations as late as June. (For more information about pollen and their season please click here.)

Which tree pollens cause hay fever?

Tree pollens that are most commonly associated with springtime allergies and hay fever are:

  • Alder
  • Ash
  • Birch (This is the number one pollen responsible for hay fever in the United States)
  • Cedar
  • Chestnut
  • Elm
  • Elder: Box and Mountain
  • Hazel
  • Hickory
  • Oak
  • Olive
  • Pecan
  • Poplar
  • Sycamore
  • Willow

Which foods have cross-reactions with tree pollen?

Cross-reactions between tree pollen and foods can occur due to something known as oral allergy syndrome. With oral allergy syndrome you may experience an itchy mouth after eating raw fruits, vegetables, or nuts. The most common tree pollen responsible for oral allergy syndrome is birch tree pollen. Other trees that tend to cross-react or cause the same oral allergy syndrome symptoms as birch tree pollen are:

  • Alder
  • Beech
  • Chestnut
  • Hazels
  • Hornbeams
  • Hop-hornbeams
  • Oak
  • Sycamore

If you have a birch tree pollen allergy or an allergy to one of the trees listed above, you may experience cross-reactions with one or more of these foods: almond, aniseed, apple, apricot, caraway, carrot, celery, cherry, coriander, fennel, hazelnut, kiwi, parsley, peach, pear, peanut, plum, and soybean. (To see a detailed oral allergy syndrome food list please click here).

How do you diagnose and treat tree pollen allergies?

For more information regarding the diagnosis of tree pollen allergies related to oral allergy syndrome please click here.

For more information regarding the treatment of tree pollen allergies related to oral allergy syndrome please click here.

For more information regarding tree pollen allergies related to hay fever please click here.



Disclaimer: The information contained in this site is for educational purposes only, and should not be used as a substitute for a licensed physician. Please see your physician for diagnosis and treatment of any concerning symptoms or medical condition. Click here to read the full disclaimer.
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