Western ragweed

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Western ragweed stem

Western ragweed

Western ragweed

Western ragweed

Western ragweed leaves

Western ragweed staminate heads

Western ragweed leaf

Western ragweed

Morphology

Stem

Erect, branched above.

Leaves

Opposite below, alternate above; petiole 0 to 1.2 inch; blade deltate to lanceolate in outline, .8 to 5.6 inches long, .4 to 2 inches wide, pinnately toothed to 1-pinnately lobed, base wedge-shaped to truncate, ultimate margins entire or toothed, surfaces hirsute to strigose.

Inflorescence

Heads discoid, unisexual, pistillate below staminate, staminate usually in raceme-like to spike-like arrays.

Flower

Pistillate heads: phyllaries 12-30(-80) in 1-8 series, outer ones distinct or connate, inner ones connate, eventually forming hard bur with free tips becoming tubercles or spines; floret 1; corolla absent. Staminate heads: peduncle short; involucres cup-shaped to saucer-shaped, 1/12 to 1/5 inch wide, minutely hairy; phyllaries 5-16 in 1 series, connate; receptacles flat to convex, chaff bracts spatulate to linear; florets 5-15(-30); corolla white to purple, funnelform, lobes 5.

Fruit

Achenes ovoid to fusiform, enclosed in bur; burs nearly pyramidal to globose, 1/12 to 1/8 inch, minutely hairy, spines or tubercles 0 or 1-6, mostly distal, tip straight; pappus absent.

Ecology

Habitat

Tallgrass, mixed-grass, shortgrass, sand, and sandsage prairies, pastures, roadsides, disturbed sites

Distribution

Occurs statewide

Practical Information

Uses

Pueblo women drank a tea made from the plant in cases of difficult labor at childbirth, the Kiowa applied a decoction as a wash for sores on humans or on horses, and the Cheyenne drank a tea of ground leaves and stems to treat colds, bowel cramps, bloody stools, and constipation.

Additional Notes