Pollen Allergen

Birch Look-alikes

Carpinus sp., (hornbeams), Ostrya sp., (hop-hornbeams) and Corylus sp. (hazels) are related to the birch and alder and cross-reactions can occur. The hornbeams grow in the eastern parts of the U.S. and from Nova Scotia to eastern Manitoba in Canada. The hazels range from the East to Wyoming in the U.S. and from Newfoundland to British Columbia in Canada. We count the hornbeams and the hop-hornbeams in the birch-look-alike category. They pollinate mostly in May. The hazels pollinate early and the season is in March or early April depending on the location.

Myrica sp., gale or sweet gale pollen resemble the birch family and are included in the birch-look-alikes as well as other Myrica species which includes the bayberries. Sweet gale is found throughout Canada and parts of the northeastern and northwestern coastal United States. The season occurs generally at the same time as birch and it is difficult to differentiate them microscopically. The Myrica are considered to be moderately allergenic.

Last Updated: 14 October 2009

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