Common ragweed

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Common ragweed

Common ragweed

Common ragweed staminate inflorescence

Common ragweed

Common ragweed leaf

Common ragweed leaf

Morphology

Stem

Erect, branching above, rough, variously hairy with long spreading and/or shorter, appressed hairs.

Leaves

Opposite lower leaves, alternate upper leaves; stalks .4 to 1.2 inches long; ovate or elliptic in outline, 1.4 to 4 inches long, to 2.8 inches wide; once or twice deeply pinnately-divided; ultimate lobes lanceolate to narrowly oblong; margins entire or few-toothed; surfaces pubescent, gland dotted; undersurface often with longer hairs along main veins; upper leaves less divided, nearly sessile.

Inflorescence

Monoecious (staminate and pistillate heads occur at different locations on same plant); heads of staminate florets on short stalks in spike-like racemes, terminal; heads of pistillate florets in clusters in leaf axils below staminate inflorescences.

Flower

Greenish-yellow; staminate heads shallowly saucer-shaped, 1/12 to 1/6 inch wide; florets 12-20+; pistillate heads egg-shaped, 1/8 inch long, 1-flowered, pubescent or nearly glabrous.

Fruit

Bur-like, egg-shaped, 1/8 to 1/5 inch long, hard, formed by floral bracts; beak 1/25 to 1/12 inch long, surrounded by 5-7 short blunt spine-like projections; seed 1, small.

Ecology

Habitat

Disturbed sites, roadsides, waste areas, prairies, pastures, stream banks, pond and lake margins, old fields, fallow fields; wet to dry soils.

Distribution

All but southwest corner of Kansas

Reproduction

Seeds

Practical Information

Toxicity

Accumulates nitrates but is rarely consumed in large enough quantities to cause poisoning. Will cause digestive upset in cattle. May cause skin irritation due to volatile oils.

Forage Value

Very limited forage value for livestock due to low palatability. Upland game birds, wild turkeys, songbirds, and small mammals will eat the fruits.

Uses

Native Americans steeped the leaves and took the tea for fevers, pneumonia, and to stop vomiting and used it as a wash for hives and swellings. They applied the crushed leaves to insect bites and used the plant for toilet paper.

Additional Notes