Perennials, 35-110(-150) cm; taprooted, spreading by rhizomes. Stems 1-30(-100), ascending to erect (sometimes reddish brown, sometimes ± brittle), appressed-strigose, sparsely to moderately long-hirsute, eglandular or sparsely to moderately stipitate-glandular, more densely so distally; axillary fascicles absent. Leaves: proximal cauline subpetiolate to sessile, blades oblanceolate, 38-73 cm × 6-15(-18) mm, bases cuneate, margins flat, sparsely serrate, strigoso-ciliate, with a few long cilia proximally, faces moderately long-strigose, eglandular or sparsely to moderately stipitate-glandular; distal sessile (usually spreading, sometimes perpendicular), blades usually narrowly to broadly oblanceolate, rarely obovate or ovate, little reduced distally (not stiff), margins sparsely serrate (not long-ciliate), faces moderately strigose, sparsely to moderately stipitate-glandular. Heads (1-)5-24, usually in open to congested corymbiform arrays, sometimes borne singly, on long peduncular branches. Peduncles 5-35 mm, short-hispido-strigose, sometimes stipitate-glandular; bracts 1-3, proximal leaflike, becoming linear-lanceolate, less hairy and more stipitate-glandular distally, larger bracts subtending heads absent or very rare. Involucres cylindric to campanulo-hemispheric, 7-9(-10.5) mm. Phyllaries in 4-5 series, outer and mid narrowly triangular, unequal, margins hyaline, fimbriate-ciliate apically, faces sparsely strigose, eglandular or sparsely to moderately stipitate-glandular. Ray florets 16-29(-38); laminae 10.5-17(-21.5) × 1-2(-2.6) mm. Disc florets (23-)32-66; corolla barely ampliate, 5-6.6 mm, glabrous, lobes 0.5-1 mm, glabrous or glabrate. Cypselae monomorphic, compressed obconic, 1.7-3.9 mm, ribs 7-10 (often brownish), faces moderately strigose; pappi off-white, outer of linear scales 0.2-1 mm, inner of bristles 5-7 mm, longest weakly clavate. Chance introductions (usually emphemeral) of Heterotheca camporum have occurred in Michigan, New Jersey, and likely other eastern states. Heterotheca camporum has well-developed serrations along the margins of its distal cauline leaves, which no other species has, although basal leaves in some species may have one or two serrations distally.
Like a robust form of no. 1 [Chrysopsis villosa (Pursh) Nutt.], 4-10 dm, but with slender creeping rhizomes as well as a taproot; rather coarsely and often only thinly hairy; lvs 3-7 cm נ8-20 mm, generally with a few sharp, small teeth; invol 8-11 mm; disk mostly 1.2-2.5 cm wide; rays ca 21 to ca 34, ca 1 cm; achenes 6-12-nerved; 2n=36. (C. villosa var. c.) Typically a prairie sp. of Mo. to Ind. and Ill., but recently intr. and becoming abundant as a weed along roadsides and in fields in se. U.S., well established in Va., and to be expected elsewhere along the s. margin of our range. The weedy form is more glandular and has been described as var. glandulissima (Semple) Cronquist. July-Sept.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.