This species has been confused with several other taxa (Cr, FNA 21), and has been reassessed across southeastern states (Sm, F, W; G. Nesom, pers. comm.). Though originally known mostly from Tex. and Okl. (where often confused with the Ozark-centered S. radula Nutt.), it extends east to c. Tenn., Ala. and n. Ga. (TENN), and it may be expected in w. Ky. It has been reported from adjacent Robertson Co., Tenn. (UCHT). S. asperrimum resembles more hairy forms of integrifolium or asteriscus (sensu stricto). Like integrifolium, its involucral bracts have pubescent surfaces, although these are usually glandular (versus usually not so). Also like integrifolium, asperrimum has mostly sessile, cordate-clasping leaf-bases; but mid-stem to upper leaves are mostly alternate. Like asteriiscus (sensu stricto), it tends to have has relatively congested inflorescenes. It differs from asteriscus in its glandular involucres; also in its achenes, which have relatively broad ca. 2 mm wings and deep 2-4 mm sinuses (as in integrifolium); its leaves are harshly scabrous-hispid (versus usually thinly scabrous-hispid to glabrous), mostly opposite below to alternate above (versus opposite); its stems have spreading hairs up to 1+ mm long (versus mostly hispid to almost glabrous and often glaucous).