Common ragweed

Ambrosia artemisiifolia L. Asteraceae (Aster family)

Life cycle

Erect, branching summer annual.

common ragweed seedling
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
Common ragweed leaf.

Stems

Usually hairy, erect and branched up to 6 feet tall.

common ragweed flowering branch
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
Western ragweed sprout. Western ragweed leaf.

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