1. Dyssodia papposa (Vent.) Hitchc. (fetid marigold)

Pl. 276 c, d; Map 1170

Plants annual, aromatic, with taproots. Stems 10–50 cm long, erect to loosely ascending from a spreading base, several- to more commonly many-branched (especially toward the tip), with several inconspicuous, fine longitudinal ridges and grooves toward the tip (occasionally also somewhat angled), sparsely to moderately pubescent with short, curved or curled hairs, sometimes nearly glabrous toward the base. Leaves opposite or the uppermost few alternate, mostly sessile, the bases of each pair slightly expanded and wrapped around the stem. Leaf blades 1–5 cm long, elliptic to ovate in outline, 1 or 2 times pinnately dissected with 7–15 primary lobes, the ultimate segments linear to narrowly linear, the margins otherwise entire or occasionally with a few irregular teeth, the surfaces glabrous or sparsely short-hairy and dotted with scattered, brownish yellow, sessile oil glands. Inflorescences of solitary, short-stalked to nearly sessile heads at the branch tips. Heads radiate. Involucre 6–10 mm long, more or less urn-shaped to narrowly bell-shaped, the disc 2–4 mm in diameter, the bracts in 2 unequal series. Involucral bracts 10–21, the surface glabrous but dotted or lined with conspicuous, sessile, yellowish brown oil glands, those of the outer series 4–9, 2–5 mm long, linear, free, green, the margins usually noticeably fringed; those of the inner series 6–12, 6–9 mm long, oblong-obovate to elliptic, somewhat thickened along the midnerve toward the base, fused at the base, greenish yellow and usually pinkish-tinged, the margins inconspicuously hairy. Receptacle shallowly convex, not elongating as the fruits mature, with minute, irregular ridges around the attachment points of the florets. Ray florets 4–8, pistillate (with a 2-branched style exserted from the short tube at flowering), the corolla 2–4 mm long, inconspicuous, yellow to orangish yellow. Disc florets 12–50, perfect, the corolla 2.5–3.5 mm long, brownish yellow, the tube not expanded at the base or persistent at fruiting, glabrous. Style branches with the sterile tip elongate and truncate at the tip. Pappus of 18–20 slender scales, 2.0–3.5 mm long, white with purplish-tinged tips or orangish yellow, each scale dissected irregularly into 5–10 ascending bristles. Fruits 3.0–3.5 mm long, narrowly oblanceolate to narrowly wedge-shaped in outline, 3–5-angled and slightly flattened, the surface moderately pubescent with silky, ascending hairs, especially along the angles, dark gray to black. 2n=26. May–October.

Scattered in most of the state but uncommon in the eastern half of the Ozark Division and apparently absent from the Mississippi Lowlands (U.S., Canada, Mexico, Central America; introduced in South America). Upland prairies, loess hill prairies, glades, and banks of streams; also pastures, levees, roadsides, and open, disturbed areas.

Plants of fetid marigold often form a dense, narrow band at the edge of the asphalt along highways. Their strong disagreeable odor and bad flavor cause livestock to avoid the species.