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Grindelia squarrosa

Species category

Weed

Common name

curlycup gumweed, curlytop gumweed, gumweed, rosinweed, tarweed

Diagnostic characters

Planting unit

AcheneAchene:
A dry, hard, one-chambered, one-seeded indehiscent fruit, as in buckwheat (Fagopyrum) or sunflower (Helianthus). The fruit wall is not united with the seed coat.

Shape

ObovateObovate:
Inverted egg shaped with apical end the broadest.

Size

  • Length 2–3 mm 
  • Width 1–1.5 mm 
  • Thickness 0.7–1 mm 

Color

Yellow

Texture

Smooth

Other structures

ApicalApical:
The distal end of the fruit or seed away from the point of attachment or attachment scar.
 collar squared off; many irregular longitudinal ribs.

Identification notes

ApicalApical:
The distal end of the fruit or seed away from the point of attachment or attachment scar.
 shoulders are not rounded, but are squared off. Longitudinal ribs are closely spaced around the acheneAchene:
A dry, hard, one-chambered, one-seeded indehiscent fruit, as in buckwheat (Fagopyrum) or sunflower (Helianthus). The fruit wall is not united with the seed coat.
, but they are not regular in size and spacing.

Noxious weed seed categories

Not listed

AOSA examination list

Not included

Nomenclature

Family

Asteraceae

Valid name

Grindelia squarrosa (Pursh) Dunal

From Left to Right: 1. Grindelia squarros 2.  Rhaponticum repens. Grendalia squarrosa on the left has more distinct longitudinal ridges and squared shoulders at the stylar end. Rhapontium ( Acroptilon) repens has smoother and rounded shoulders.
From Left to Right: 1. Grindelia squarros 2. Rhaponticum repens. Grendalia squarrosa on the left has more distinct longitudinal ridges and squared shoulders at the stylar end. Rhapontium ( Acroptilon) repens has smoother and rounded shoulders.
Grindelia squarrosa. Achenes with a squared apical collar.
Grindelia squarrosa. Achenes with a squared apical collar.