Ragweeds - COMMON/GIANT
There are 2 types of ragweed found in sweet corn; Common ragweed and Giant ragweed.
Scientific Names: Common ragweed, Ambrosia artemisiifolia L.; Giant ragweed, Ambrosia trifida L.
Other Names: Common ragweed is also called petite herbe à poux, Short ragweed, ambroisie a feuilles d’armoise. Giant ragweed is also called grande herbe à poux, Great ragweed, Kinghead, Tall ragweed, ambroisie trifide
Family: Composite or Aster Family (Compositae)
General Description: Annual, reproducing only by seed.
Habitat: Common ragweed is one of the most abundant weeds of cultivated land throughout southern Ontario, but is rare or absent in northern and north-western parts of the province. It also occurs in gardens, flower borders, poorly kept lawns, edges of sidewalks, roadsides, fence lines, waste places, and in disturbed areas in pastures and meadows. Giant ragweed occurs in river valleys, meadows, roadsides and occasionally in cultivated fields in the south-western portion of southern Ontario.
Seedlings
Common Ragweed | Giant Ragweed |
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Stems
Common Ragweed | Giant Ragweed |
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Leaves
Common Ragweed | Giant Ragweed |
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Flowers
Common Ragweed | Giant Ragweed |
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Often Confused With
Goldenrod (Goldenrod has a very conspicuous bright yellow inflorescences during the ragweed hay fever season of late summer and autumn).
Caution:
Common ragweed is the most important cause of hay fever during August and September. Although inconspicuous and not recognized by most people, the tiny male flower beads hanging on their slender stalks produce hug quantities of very light pollen. As the pollen falls from these hanging flowers, it is caught by the wind and may be carried for distances greater than 200 km (125 miles). Hay fever sufferers, therefore, may be affected by pollen from ragweed plants far away.