This taxon may be widespread across eastern states, except towards the southwest, but its circumscription remains uncertain; the range indicated by most current authors (K) is probably wide than strumosus in its strict sense. In this sense, excluding trachelifolius, strumosus includes hexaploids (2n = 102), but perhaps no tetraploids. It has often been confused with other taxa (F; Heiser et al. 1969). Further analysis is needed, including more thorough collections from regions of overlap with eggertii and trachelifolius, which both could be treated as subspecies or varieties of strumosus. Like those other taxa, strumosus is typical of thin woods and edges on medium acid soils, and it can proliferate after forest fires. In Ky. it is largely restricted to Appalachian regions and lowlands in the Knobs, where it tends to be most common in submesic swales with more seasonal dampness than adjacent subxeric uplands. H. glaucophyllus D.M. Smith is a closely related diploid (2n = 34), largely restricted to middle elevations in the Southern Appalachians; it has been recently reported from BELL (NCU), but this record is dubious and requires verification. That species differs from strumosus in its smaller heads, with rays usually 5-8 (versus 10-20) and involucres ca. 8-9 mm wide (versus 8-20 mm); leaves may be more apruptly narrowed at base, more consistently serrate, less pubescent below and less gland-dotted (FNA 21, W).