Lanceleaf Ragweed

Ambrosia bidentata

Weed Description
Erect, branching warm-season annual that can reach 3.5 feet in height. Native to North America, lanceleaf ragweed is usually found in pastures, right-of-ways, and roadsides.

Leaves
Leaves are arranged oppositely around the base otherwise stem leaves are alternate, hairy, and lanceolate in outline. Unlobed leaves occasionally occur with a single triangular lobe or tooth on each side near the base of the leaf.

Stems
Erect, rough or hairy in the upper portions, occasionally smooth or hairless towards the base of the plant.

Flowers
Resemble those of common ragweed.

Roots
Fibrous root system from a taproot.

Identifying Characteristics
Lanceleaf ragweed has leaves that are shallowly lobed and triangular or lanceolate in outline, and contains stems and leaves are covered in hairs. Plants are perhaps most distinct in the late summer when the single terminal spike of flowers occur.

Office of Programs

University of Missouri

Lanceleaf Ragweed

Ambrosia bidentata