This is one of the species clearly native to Michigan. It does not occur very far west of the Great Lakes, except at latitudes much farther south. Typically in dry ± open forests and savannas of oak, pine, or aspen, especially at edges; fencerows, fields, roadsides, and railroads.

Some plants with distinct but short petioles and other intermediate characters are considered to be hybrids. Hybrids with H. giganteus have been named H. ×ambiguus (Torr. & A. Gray) Britton; specimens so determined have leaves resembling H. divaricatus or intermediate in shape and sparsely hairy stems. The somewhat dubious Menominee Co. material referred to H. hirsutus could conceivably be this hybrid or something approaching H. strumosus. Other intermediate plants, but with glabrous stems, have been named H. ×divariserratus R. W. Long, the other parent being H. grosseserratus.