Horseweed

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Horseweed

Horseweed inflorescence

Horseweed

Horseweed leaf

Horseweed florets

Horseweed in winter

Horseweed stem

Horseweed in winter

Horseweed florets

Horseweed

Horseweed

Horseweed

Morphology

Stem

Erect, solitary, unbranched below, occasionally branching above mid-point, coarsely hairy.

Leaves

Alternate, numerous, sessile to short-stalked, simple, oblanceolate to linear, 4/5 to 4 inches long, 1/6 to 2/5 inch wide; margins entire or lower leaves with coarse teeth; stiff-hairy along margins and on mid-vein; tip pointed; basal leaves larger, sometimes falling early; stem leaves reduced upward.

Inflorescence

Panicle, open, elongated, terminal; heads numerous, inconspicuous, bell-shaped, about 1/5 inch across; involucral bracts in 1-2 series, overlapping, lanceolate to linear, 1/10 to 1/6 inch long, greenish.

Flower

Ray florets 20-40, white or sometimes pale pink; disk florets 8-30, yellow.

Fruit

Achene, egg-shaped to oblanceolate, around 1/25 inch long, flattened, tan to pale grayish-brown, tipped with 15-25 white to tan bristles 1/12 to 1/8 inch long, enclosing small seed.

Ecology

Habitat

Waste areas, prairies, fields, roadsides, gardens, stream banks, open disturbed sites.

Distribution

Throughout Kansas

Reproduction

By seed

Practical Information

Toxicity

The leaves and flowers contain a chemical that is irritating to the skin and nostrils of horses. It has been reported toxic to sheep and cattle, but this has not been confirmed experimentally.

Uses

Native Americans steeped the leaves and took the liquid for diarrhea and stomach pains and applied the cold infusion to snake bites and pimples. The crushed plant was rubbed on sunburns and sore joints and a poultice of the crushed plant was applied to earaches and to the temples for headaches.

Additional Notes