1b. Heterotheca subaxillaris (Lamarck) Britton & Rusby subsp. latifolia (Buckley) Semple, Sida. 21: 759. 2004.
Heterotheca latifolia Buckley, Proc. Acad. Nat. Sci. Philadelphia 13: 459. 1862; H. latifolia var. arkansana B. Wagenknecht; H. latifolia var. macgregoris B. Wagenknecht; H. psammophila B. Wagenknecht; H. subaxillaris var. latifolia (Buckley) Gandhi & R. D. Thomas; H. subaxillaris var. petiolaris Benke
Outer and mid phyllaries without distinct apical tuft of hairs (sometimes distally with 1–2 coarse, scabro-strigose hairs), abaxial faces sometimes sparsely short-hairy, moderately to densely stipitate-glandular. 2n =18.
Flowering (Mar–)May–Dec. Sandy, clay and gravelly soils, grasslands, prairies, disturbed ground, roadsides, vacant lots, fields, open areas in pine and oak woods and scrub or mesquite scrub; 0–1800 m; Ala., Ariz., Ark., Calif., Colo., Conn., Del., Ga., Ill., Ind., Iowa, Kans., Ky., La., Md., Miss., Mo., Nebr., Nev., N.J., N.Mex., N.Y., N.C., Okla., Pa., S.C., Tenn., Tex., Utah, Va.; Mexico.
Subspecies latifolia occurs over much of the central and southern United States into Mexico. It lacks tufts of coarse hairs at the tip of the phyllaries (sometimes 1–2 may be present distally), which are sometimes densely stipitate-glandular. Stem height is variable throughout the range. Robust plants (to 2 m) occurring in Arizona, New Mexico, and adjacent Texas have been treated as Heterotheca psammophila, but they grade into those treated as subsp. latifolia farther east on the prairies and eastward. The latter have been split into weakly defined varieties not recognized here. The more western plants tend to have more linear-lanceolate, more densely glandular phyllaries. Plants from Long Island, New York, have 0–3(–6) hairs distally on the phyllaries.