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Ambrosia trifida
Ambrosia trifida L.
Great Ragweed, Giant Ragweed
Asteraceae (Aster Family)
Synonym(s):
USDA Symbol: amtr
USDA Native Status: L48 (N), CAN (N)
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.
Plant Characteristics
Duration: AnnualHabit: Subshrub
Size Notes: Up to about 12 feet tall, often shorter.
Fruit: Fruit is a cypsela (pl. cypselae). Though technically incorrect, the fruit is often referred to as an achene.
Bloom Information
Bloom Color: Green , BrownBloom Time: Jun , Jul , Aug , Sep , Oct
Distribution
USA: 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 , WYCanada: 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.
Growing Conditions
Light Requirement: Part Shade , ShadeSoil Moisture: Moist
Butterflies and Moths of North America (BAMONA)
Bordered Patch (Chlosyne lacinia) Adult Food Source |
National Wetland Indicator Status
Region: | AGCP | AK | AW | CB | EMP | GP | HI | MW | NCNE | WMVE |
Status: | FAC | FAC | FAC | FAC | FAC | FAC | FAC |
From the National Organizations Directory
According 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
Bibliography
Bibref 417 - Field Guide to Medicinal Plants and Herbs of Eastern and Central North America (2000) Foster, S. & J. A. DukeBibref 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
Search More Titles in Bibliography
Web Reference
Webref 3 - Flora of North America (2014) Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.Additional resources
USDA: Find Ambrosia trifida in USDA PlantsFNA: Find Ambrosia trifida in the Flora of North America (if available)
Google: Search Google for Ambrosia trifida
Metadata
Record Modified: 2022-10-12Research By: TWC Staff