The poplars, aspens and cottonwoods are wind-pollinated. They are considered mildly allergenic and are abundant in most areas of Canada and the United States. The species vary throughout North America. The seasons are also diversified, starting from February to May depending on the location and climate -- the West Coast season being much earlier (January and February) when compared to the mid-western states or provinces (March to May). The same applies from the north to the south, with the season in the southern states starting much earlier than in the northern part of the country.
Some species, such as the cottonwoods, shed a residue commonly called June snow. Although this residue is often mistaken for pollen, it is not and does not carry the antigen that is present in the pollen. However, it does often contain fungi such as Cladosporium sp., and can elicit allergic reactions from those sensitive to these fungal spores.
Last Updated: 13 July 2009
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