There are over 1000 species of grasses and just a few species are considered allergenic. It is difficult to differentiate the species under a microscope so they are grouped together as the gramineae family. Counts can get very high so grasses, in general, are considered a major allergen. Grass pollen is most abundant in June and July. Some species, particularly in parts of the United States and Western Canada, bloom in May. Certain species of grass in the southern states are important allergens almost year-round. On a worldwide scale, the grasses are clearly the most important allergenic pollen producing plant family
Grass allergies are somewhat of a special case, as the allergen is introduced into the air when the grass is mowed. As such, people are being primed to the antigen of the plant long before grass pollen is released, and allergic reactions are often elicited before significant pollen counts are observed.
Last Updated: 14 October 2009
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