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Pollen and Mold Center
Composite or Ragweed Family (Compositae Family) - RAGWEED

Get readings about Ragweed aeroallergens.

Weed pollen is dominant in the Fall.
Ragweed blooms from Mid-July to September.

Ragweed tribes in Missouri:
  • Sunflower (Heliantheae)
  • Ragweed, Cocklebur, Marshelder, Franseria (Ambrosieae)
  • Sneezeweed, Marigold, Feverfew (Helenieae)
  • African Daisy (Arctotideae)
  • Calendula (Calenduleae)
  • Straw Flower (Inuleae)
  • Aster, Goldenrod, Groundselbush, Desert Broom (Astereae)
  • Ironweed (Vernonieae)
  • Dog Fennel, Joe-pye Weed (Eupatorieae)
  • Chamomile, Yarrow, Pyrethrum, Chrysanthemum, Wormwood, Sage (Anthemideae)
  • Ragwort, Butterweed (Senecioneae)
  • Thistle, Burdock (Cardueae)
  • Gerbera Daisy (Mutisieae)
  • Chicory, Lettuce, Dandelion (Cichorieae)
Facts about Ragweed
  • Common ragweed (Ambrosia bidentata) is a coarse, hairy plant with a slightly noxious odor and no pretty flowers.
  • There are 17 species of ragweed in North America.
  • Ragweed pollen amounts increase with heavy spring rain and hot, dry pollen season. Pollen amounts decrease when rain and humidity is too great during the blooming period.
  • Ragweed (Ambrosia bidentata) is the most important allergenic plant of North America. It produces large quantities of small, buoyant pollen.
  • The strongest antigen, antigen E, is found in Ambrosia and Franseria.
  • Other strong antigens are found in sagebrushes (Artemisia) and marshelders (Iva).
  • Cocklebur (Xanthium) causes occasional allergy problems, but is not abundant in the air.
  • Goldenrod (Solidago) is insect-pollinated and seldom an allergy problem.
  • Dog fennel (Anthemis Cotula) is partly insect-pollinated, but does have a large amount that is airborne. This blooms late summer to December.
  • Eating sunflower seeds, drinking chamomile tea, and smelling pyrethrum insecticide, marigolds, or chrysanthemums have all been reported to cause allergic reactions.
  • Wormwood (Artemisia) and mugwort (Artemisia vulgaris) are prevalent in the central states and produce pollen in the late summer and fall.