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Curlycup Gumweed, Curlytop Gumweed - Grindelia squarrosa


Family: Asteraceae - Aster family Genus Common Name: Gumweed Native Status: NativeDicot Annual Biennial Perennial Herb Leaves:Alternate
Grindelia squarrosa - Curlycup Gumweed, Curlytop Gumweed.
Grindelia (Gumweed) is a genus of about 30 species of the Americas, native to parts of South America, Mexico, and the United States, with a few species have spread into Canada as alien. About 18 species are found in the United States, most in the west to the Great Plains, but with a few east of the Mississippi.

Grindelia squarrosa is the most widely distributed species of Gumweed in the United States. It is native to the western part of the country into the Great Plains, and has naturalized in much of the rest of the country outside of the deep south. It is considered invasive in parts of its range, spreading rapidly in overgrazed grasslands and dry waste places.

Found in:
AR, AZ, CA, CO, CT, DE, IA, ID, IL, IN, KS, KY, MA, MD, ME, MI, MN, MO, MT, ND, NE, NH, NJ, NM, NV, NY, OH, OK, OR, PA, RI, SD, TN, TX, UT, VA, VT, WA, WI, WY
Grindelia squarrosa

Distribution of Grindelia squarrosa in the United States and Canada:
Map unavailable.
Map courtesy of The Biota of North America Program.
Map color key

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Site: Carbon County, Wyoming Date: 2019-August-11Photographer: Gerald C. Williamson
Nikon D7000
Tamron SP 90MM f/2.8 AF Macro
The flower head of Grindelia squarrosa has yellow disc and ray florets. There are usually 24 to 36 ray florets, although there are occasionally none, and the are up to about 1/2 inch long.
Grindelia squarrosa
Site: Carbon County, Wyoming Date: 2019-August-11Photographer: Gerald C Williamson
Nikon D7000
The common name for the genus is Gumweed - derived from the gummy white latex that exudes onto the flower head.
Click on the photo for a larger image
Grindelia squarrosa
Site: Carbon County, Wyoming Date: 2019-August-11Photographer: Gerald C Williamson
Nikon D7000
The species epithet - squarrosa - comes from the stiff and spreading phyllaries. Most of the phyllaries are strongly reflexed at the tips to be hooked or looped.
Click on the photo for a larger image
Grindelia squarrosa
Site: Carbon County, Wyoming Date: 2019-August-11Photographer: Gerald C Williamson
Nikon D7000
Grindelia squarrosa has glabrous stems up to about about 4 feet tall. The flower heads are in loose arrays; occasionally singly.
Click on the photo for a larger image
Grindelia squarrosa
Site: Carbon County, Wyoming Date: 2019-August-11Photographer: Gerald C Williamson
Nikon D7000
The alternate leaves have rounded teeth and are usually under about three inches long. They are partially clasping the stem.
Click on the photo for a larger image
Grindelia squarrosa
References used for identification and information:
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Grindelia squarrosa initially published on USWildflowers.com 2019-11-13; Updated 2019-11-13

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All content except USDA Plants Database map Copyright Gerald C. Williamson 2024
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Code Update 20230302