Plant Allergy Overview
Allergenicity
Moderate
Pollen Season
Winter Spring
Type
Tree
Sub-Type
Deciduous
Allergy Information
All species have windborne pollen which has been reported to be a significant allergenic cause. People sensitive to one alder species are usually sensitive to all species.
Genus Details
Alders are deciduous trees or large shrubs that often grow together in moist soils in wooded areas of North America. All species have separate drooping male and upright female flowers on catkins of the same plant. Flowering precedes the opening of leaf buds and usually occurs during January to April depending on latitude and elevation.
Pollen Description
Pollen grains of Alnus are oblate to oblate-spheroidal and usually 4-5 porate. Their exinous thickened bands that extend in pairs from aperture to aperture distinguish the grains.
Pollen grains vary in size from 19-21 x 23-30 micrometers.
Genus Distribution
The shaded areas on the map indicates where the genus has been observed in the United States.
Species in Alder Genus
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