Ambrosia trifida L.
Great Ragweed, Giant Ragweed
Asteraceae (Aster Family)
USDA Symbol: AMTR
A tall, rough, hairy plant with elongated, terminal clusters of nodding male flower heads above few clusters of female flower heads; some plants with hundreds of heads.
This is the giant among the ragweeds, reaching towering heights and possessing long flower spikes. The pollen of ragweeds is spread by wind rather than by insects. Can be invasive, especially in disturbed areas such as a streambank. Pollen from Great Ragweed contains many antigens that cause hay fever.
From the Image Gallery
Bloom InformationBloom Color: Green , Brown
Bloom Time: Jun , Jul , Aug , Sep , Oct
DistributionUSA: AL , AR , AZ , CA , CO , CT , DC , DE , FL , GA , IA , ID , IL , IN , KS , KY , LA , MA , MD , ME , MI , MN , MO , MS , MT , NC , ND , NE , NH , NJ , NM , NY , OH , OK , OR , PA , RI , SC , SD , TN , TX , UT , VA , VT , WA , WI , WV , WY
Canada: AB , BC , MB , NB , NS , ON , PE , QC , SK
Native Distribution: Throughout much of North America, except far north.
Native Habitat: Waste places, fields, and roadsides.
Butterflies and Moths of North America (BAMONA)
Bordered Patch |
Learn more at BAMONA
Adult Food Source
National Wetland Indicator Status
From the National Organizations DirectoryAccording to the species list provided by Affiliate Organizations, this plant is on display at the following locations:
Fredericksburg Nature Center - Fredericksburg, TX
Brackenridge Field Laboratory - Austin, TX
Texas Master Naturalists - Lost Pines Chapter - Bastrop, TX
Natural Biodiversity - Johnstown, PA
BibliographyBibref 417 - Field Guide to Medicinal Plants and Herbs of Eastern and Central North America (2000) Foster, S. & J. A. Duke
Bibref 1186 - Field Guide to Moths of Eastern North America (2005) Covell, C.V., Jr.
Bibref 1185 - Field Guide to Western Butterflies (Peterson Field Guides) (1999) Opler, P.A. and A.B. Wright
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Additional resourcesUSDA: Find Ambrosia trifida in USDA Plants
FNA: Find Ambrosia trifida in the Flora of North America (if available)
Google: Search Google for Ambrosia trifida
MetadataRecord Modified: 2016-01-13
Research By: TWC Staff