Senecio integerrimus is a species of flowering plant in the aster family known by the common names lambstongue ragwort[1] and tall western groundsel.

It is native to western and central North America, where it grows in grassland, forest, and other habitat.

It is a biennial or perennial herb producing one or a few erect stems 20 to 70 centimeters (8 to 27+1⁄2 in) tall from a caudex with fleshy shallow roots.

[2] The linear to lance-shaped or triangular leaves are primarily basal,[2] with blades up to 25 cm (10 in) long.

The inflorescence bears several flower heads in a cluster,[2] the middle, terminal head often largest and held on a shorter peduncle, making the cluster look flat.