GIANT RAGWEED
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GIANT RAGWEED

Ambrosia trifida
SUNFLOWER FAMILY (Asteraceae)

Identification

  • Flowering time - July, August, September
  • Common in disturbed areas at FF & NW
  • One of our larger plants
  • Long, slender green spikes at tips of branches
  • Large leaves with 3-5 lobes
  • GIANT RAGWEED
Click on each photo thumbnail to enlarge.

This native annual often grows to well over 6 feet tall. The large, opposite leaves have 3-5 lobes (A). The yellow male flowers (B) are on numerous elongated, slender spikes up to 8 inches long (A). The inconspicuous female flowers are found just below the male flowers.

Common along sunny roadsides, trails and disturbed ground at both Fontenelle Forest and Neale Woods. Flowers from July through September.

Pollination is by wind. Ragweeds are a major cause of hay fever in our area. The pollen of ragweeds is collected commercially and used in preparations for the treatment of allergies. Native Americans used the crushed leaves of this plant to treat insect bites.

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