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Ambrosia psilostachya (Cuman ragweed)
Williams, Pam

Ambrosia psilostachya

Ambrosia psilostachya DC.

Cuman Ragweed, Western Ragweed, Perennial Ragweed, Common Ragweed

Asteraceae (Aster Family)

Synonym(s): Ambrosia californica, Ambrosia coronopifolia, Ambrosia cumanensis, Ambrosia psilostachya var. californica, Ambrosia psilostachya var. coronopifolia, Ambrosia psilostachya var. lindheimeriana, Ambrosia rugelii


USDA Native Status: L48 (N), CAN (N)


From the Image Gallery

13 photo(s) available in the Image Gallery

Plant Characteristics

Duration: Perennial
Habit: Herb
Root Type: Fibrous
Leaf Arrangement: Alternate
Leaf Shape: Lanceolate
Leaf Pubescence: Hirsute
Leaf Margin: Entire
Leaf Base: Cuneate , Truncate
Breeding System: Flowers Unisexual , Monoecious
Inflorescence: Spike
Size Notes: Up to about 3 feet tall.
Fruit: Fruit is a cypsela (pl. cypselae). Though technically incorrect, the fruit is often referred to as an achene.

Bloom Information

Bloom Color: White , Green
Bloom Time: Jul , Aug , Sep , Oct
Bloom Notes: Bloom season may extend to December.


USA: AL , AR , AZ , CA , CO , CT , FL , GA , IA , ID , IL , IN , KS , LA , MA , ME , MI , MN , MO , MT , NC , ND , NE , NH , NM , NV , NY , OH , OK , OR , PA , SC , SD , TN , TX , UT , VT , WA , WI , WY
Canada: AB , BC , MB , ON , PE , QC

Growing Conditions

Light Requirement: Sun , Part Shade
Soil Moisture: Dry

Find Seed or Plants

Find seed sources for this species at the Native Seed Network.

National Wetland Indicator Status

This information is derived from the U.S. Army Corps of Engineers National Wetland Plant List, Version 3.1 (Lichvar, R.W. 2013. The National Wetland Plant List: 2013 wetland ratings. Phytoneuron 2013-49: 1-241). Click here for map of regions.

From the National Organizations Directory

According to the species list provided by Affiliate Organizations, this plant is on display at the following locations:

Lady Bird Johnson Wildflower Center - Austin, TX
Sibley Nature Center - Midland, TX
Brackenridge Field Laboratory - Austin, TX
Patsy Glenn Refuge, c/o Wimberley Birding Society - Wimberley, TX
Nueces River Authority - Uvalde, TX
Stengl Biological Research Station - Smithville, TX
Natural Biodiversity - Johnstown, PA
Native Seed Network - Corvallis, OR

Web Reference

Webref 38 - Flora of North America (2019) Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
Webref 23 - Southwest Environmental Information Network (2009) SEINet - Arizona Chapter

Additional resources

USDA: Find Ambrosia psilostachya in USDA Plants
FNA: Find Ambrosia psilostachya in the Flora of North America (if available)
Google: Search Google for Ambrosia psilostachya


Record Modified: 2022-11-09
Research By: TWC Staff

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