Grindelia squarrosa (Pursh) Dunal

Grindelia squarrosa plant

Family - Asteraceae

Stems - To 1 m, erect, glabrous or sparsely hairy near base, usually with ascending branches toward the tip. Plants usually biennial.

Grindelia squarrosa stemStem and leaves.

Grindelia squarrosa rootRoot.

Leaves - Stem leaves sessile, to 7 cm, oblanceolate to oblong or ovate, truncate to shallowly cordate at the base and slightly to moderately clasping the stem, mostly bluntly pointeded, the margins with moderate to numerous relatively blunt teeth, these mostly with a thickened or glandular tip, the surfaces appearing strongly resinous with dense glandular dots, these conspicuously darker than the surrounding leaf tissue, otherwise glabrous. Basal leaves similar to lower stem leaves, absent at flowering.

Grindelia squarrosa leaf

Inflorescence - Solitary heads or loose terminal clusters in branch tips, occasionally a few heads in leaf axils.

Involucre - Receptacle 1-2 cm in diameter. Involucre 6-11 mm long, the bracts in 5-9 unequal series, linear, strongly curled or recurved

Grindelia squarrosa involucreInvolucre.

Ray flowers - Ray florets 20-40 (rarely absent), pistillate, with ligules 7-15 mm long.

Disk flowers - Perfect, sometimes functionally staminate at inside or outside of disk, the corollas 3.5-6.5 mm long. Pappus of 2-8 slender awns, 2.5-6.0 mm long, these usually barbed, not persistent at fruiting (usually shed individually as the fruit matures), off-white to straw-colored.

Grindelia squarrosa flowersYoung flower head.

Grindelia squarrosa flowersMaturing flower head.

Grindelia squarrosa gumHeads exuding gum.

Flowering - July - September.

Habitat - Waste ground, roadsides, railroads.

Origin - Native to the U.S.

Other info. - This easily identifiable species can be found scattered throughout Missouri but is absent from most of the south and central portions of the state. It is very common throughout the western half of the U.S. The plant can be identified by its gummy-sticky heads and recurved bracts. There are currently three varieties recognized in Missouri: var. nuda, which lacks ray florets, var. quasiperennis, which has entire or inconspicuously toothed leaf margins, and var. squarrosa, which conforms to the descriptions above and the most common in this state. The taxononmy of the complex is still not fully understood.

G. squarrosa was used widely by natives to treat a variety of ailments ranging from asthma to cancer. It is also believed to have sedative properties.

The species epithet "squarrosa" refers to the spreading and recurved bracts of the involucre.

Photographs taken in Marquette, MI., 9-5-2003 (DETenaglia); also near Ravenna Lake State Recreation Area, Buffalo County, NE, 8-21-2012, and near Moorcroft, Crook County, WY, 8-22-2012 (SRTurner).


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