Grindelia Willdenow. Gum-plant, Tarweed, Rosinweed, Gumweed.

Key to Grindelia

A genus of about 55 species, herbs and shrubs, of w. North America and South America.

ID notes: Grindelia fits poorly into finite morphological boxes due to the wide variability in almost all of its major character states within species and the genus as a whole (hence, why it is keyed in multiple locations in the Asteraceae key to genera; some of these perhaps truly "fail-safe").

Ultimately the pappus of Grindelia (even when setiform scales are trending barbellate) is markedly different than the truly barbellate-barbellulate (and often much more numerous) bristles of other yellow-flowered, radiate composites with basal/alternate leaves (Key K).

Nonetheless, some of the general characters distinguishing this genus include cauline leaves often toothed with faces gland-dotted, phyllaries gummy and usually with apices curved or hooked, large globular heads, and a pappus of a few falling scales (but, see both Prionopsis and Grindelia in Asteraceae key).

Ref: Bartoli & Tortosa (2012); Cronquist (1980); Nesom (2019d); Strother & Wetter (2006a) In Flora of North America Editorial Committee (2006b). Show full citations.

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