Common ragweed
June 10, 2015
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EmailAmbrosia artemisiifolia L. Asteraceae (Aster family)
Life cycle
Erect, branching summer annual.
Common ragweed seedling.
Leaves
Cotyledons are thick and oval to spatula-shaped. Leaves are fernlike, once or twice compound, and usually hairy. Upper leaves are alternate; lower leaves may be opposite or alternate with distinct petioles.
Common ragweed leaf.
Stems
Usually hairy, erect and branched up to 6 feet tall.
Common ragweed flowering branch.
Flowers and fruit
Flowers are generally inconspicuous, found on terminal branches. They produce prolific amounts of pollen. The seed is enclosed in a single-seeded, woody fruit with several spikes resembling a crown.
Reproduction
Seeds.
Similar weeds
Giant ragweed (A. trifida L.)
Differs by having cotyledons three to four times larger; three- to five-lobed leaves opposite in arrangement; and a height that may reach 15 feet. (See pages 62-63.)
Western ragweed (A. psilostachya DC.)
Differs by having a perennial nature with prolific creeping roots, densely hairy leaves and a height typically not above 4 feet.
Western ragweed sprout. Western ragweed leaf.
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