Annuals or perennials, 50-200+ cm; fibrous-rooted. Stems minutely puberulent and sessile-glandular, usually also closely arachnose (hairs appressed). Leaves petiolate (petioles 10-20 mm); blades elliptic to oblong-elliptic, 6-15 × 3-7 cm, margins dentate-serrate or entire, faces glandular-puberulent or puberulent and sessile-glandular. Heads in paniculiform arrays (of rounded-convex, corymbiform clusters terminating branches from distal nodes, arrays usually resulting from axillary, strongly ascending, bracteate branches, the central axis longest and first to flower and, rarely, the only component of an array). Involucres campanulate, 4-6 × 3-4 mm. Phyllaries usually cream, sometimes purplish, minutely sessile-glandular (the outer also sparsely puberulent), sometimes glabrate. Corollas rose purplish. Pappi persistent, bristles distinct. Flowering Aug-Oct (year-round in south). Flatwoods, bottomland channels, other wet or moist freshwater habitats; 0-30 m; Ala., Ark., Del., Fla., Ga., Ill., Ind., Kans., Ky., La., Md., Miss., Mo., N.J., N.C., Ohio, Okla., Pa., S.C., Tenn., Tex., Va., W.Va. Pluchea camphorata is similar to P. odorata and rarely may hybridize with it. In P. camphorata, the phyllaries of the inner 2-3 series are thin and nearly translucent, lanceolate, and more than twice as long as deltate-ovate phyllaries of the outer series. The inner may be glandular but they are otherwise glabrous, prominently different in vestiture from the outer. The phyllaries of P. odorata are more strongly graduated and the inner are glandular and also clearly puberulent as well.
From Flora of Indiana (1940) by Charles C. Deam
This plant emits a disagreeable odor which is noticeable several feet from the plant. When any part of the plant is bruised, the odor is very strong and every one on whom I have tested it agrees that it is extremely unpleasant. The nearest approach to it is the odor of the skunk, and I think it should receive a common name to suggest its vile odor. It is local but usually common where it is found. Its habitat is swamps and sloughs in a soil that is slightly acid. Usually associated with pin oak, buttonbush, sweet gum, swamp cottonwood, Hibiscus palustris, Panicum stipitatum, and Juncus effusus var. solutus. I once found it on high ground in a logging road but this is no surprise, because I planted it in Bluffton in our garden and it grew very vigorously which shows that it will grow wherever its seeds may be deposited.
Similar to no. 2 [Pluchea odorata (L.) Cass.] in aspect, avg taller, to 2 m, sometimes perennial, and more glabrate; lvs thinner, on the avg more serrate, and more evidently petiolate, avg a little narrower and more acuminate; infl generally round-topped, often ±elongate; invol 4-6 mm, sometimes purplish, but more often not, merely granular-glandular, or nearly glabrous; disk 3-6 mm wide; 2n=20. Wet or moist, nonsaline places; Del. and Md. to n. Fla., w. to s. O., s. Ill., and e. Okla. and Tex. Aug.-Oct. (P. petiolata)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.