Great Ragweed Ambrosia trifida Linnaeus var. trifida    Synonyms: Ambrosia trifida trifida, Giant Ragweed.
Kingdom Plantae   >   Division Tracheophyta   >   Class Magnoliopsida   >   Order Asterales   >   Family Asteraceae   >   Genus Ambrosia   

Status:

Great Ragweed is common across the state. It can be found in a variety of habitats including, bottomlands, rich wood edges, roadsides, and cultivated areas.

Description:

Great Ragweed can grow to over ten feet tall. The three (rarely four or five) cleft leaves are diagnostic among Maryland herbaceous plants. Flowers are on long spikes or racemes.

Relationships:

Host to Euaresta festiva larvae.

Host to Black-smudged Chionodes Moth. Leaves are mined by the micro-moth Astrotischeria ambrosiaeella.

There are 273 records in the project database.

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Great Ragweed in Dorchester Co., Maryland (9/13/2016). Photo by Wayne Longbottom. (MBP list)

The leaves of Great Ragweed in Dorchester Co., Maryland (6/25/2013). Photo by Jim Brighton. (MBP list)

Great Ragweed in Howard Co., Maryland (9/7/2017). Photo by Bill Hubick. (MBP list)

Great Ragweed blooming in Calvert Co., Maryland (8/29/2019). Photo by Tyler Bell. (MBP list)

Great Ragweed in Worcester Co., Maryland (8/19/2012). Photo by Bill Hubick. (MBP list)

The blooms of a Great Ragweed in Talbot Co., Maryland (9/1/2013). Photo by Jim Brighton. (MBP list)

Great Ragweed in Caroline Co., Maryland (9/13/2016). Photo by Wayne Longbottom. (MBP list)

Great Ragweed growing in Harford Co., Maryland (8/19/2017). Photo by Josh Emm. (MBP list)

Great Ragweed (flowers) in Howard Co., Maryland (9/3/2013). Photo by Joanne Solem. (MBP list)

Great Ragweed (close-up) in Anne Arundel Co., Maryland (8/28/2012). Photo by Bill Harms. (MBP list)

Great Ragweed in Howard Co., Maryland (9/3/2013). Photo by Joanne Solem. (MBP list)

Great Ragweed in Howard Co., Maryland (8/24/2020). (c) johnbotany, some rights reserved (CC BY-NC). Photo by John Hall. (MBP list)

Great Ragweed in Anne Arundel Co., Maryland (8/30/2017). Photo by Tyler Bell. (MBP list)

Great Ragweed in Allegany Co., Maryland (7/21/2014). Photo by Kimberly Booth. (MBP list)

Great Ragweed in Allegany Co., Maryland (7/21/2014). Photo by Kimberly Booth. (MBP list)

Great Ragweed hosting a Calycomyza platyptera leaf mine in Worcester Co., Maryland (8/5/2018). Photo by Josh Emm. (MBP list)

Great Ragweed in Baltimore Co., Maryland (8/27/2016). Photo by Kirsten Johnson. (MBP list)

Great Ragweed in Montgomery Co., Maryland (7/3/2019). (c) pikachueevee55055, some rights reserved (CC BY-NC). Photo by pikachueevee55055 via iNaturalist. (MBP list)

Great Ragweed in Baltimore City, Maryland (6/23/2018). (c) Sam Little, some rights reserved (CC BY-NC). Photo by Sam Little via iNaturalist. (MBP list)

Great Ragweed in Baltimore City, Maryland (7/6/2019). (c) Brett M, some rights reserved (CC BY-NC). Photo by Brett M via iNaturalist. (MBP list)

Great Ragweed in Anne Arundel Co., Maryland (8/28/2012). Photo by Bill Harms. (MBP list)


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