This is a member of the Aster family.

It is a biennial or perennial herb

"Thomas Nuttall collected the first specimens of this plant for science in 1811 on the plains near the Missouri River in what is now Montana. He named the plant in his Genera of North American Plants in 1818. "Integerrimus" is from the Latin for "entire, whole, or complete" perhaps referring to the "entire" (smooth-edged) leaves or to the compact cluster of flowers.

"Senecio" is from the Latin, "senes", "old man", and refers to the pappus hairs, the tiny bristle, hair, or awn growth at the apex of the seeds in Asteraceae."(from http://www.swcoloradowildflowers.com/)