92. Tagetes L. (marigold)

Plants annual (perennials elsewhere), aromatic, with taproots. Stems erect or ascending, unbranched to several-branched, with several fine longitudinal ridges and grooves, glabrous. Leaves mostly alternate, the lowermost few sometimes opposite, mostly sessile, the bases of each pair slightly expanded and wrapped around the stem. Leaf blades 3–12 cm long, elliptic to ovate in outline, 1 or 2 times pinnately dissected with 9–25 primary lobes, the ultimate segments linear to narrowly lanceolate, the margins otherwise entire or with a few irregular teeth, the surfaces glabrous and dotted with scattered, brownish yellow, sessile oil glands. Inflorescences of solitary, mostly long-stalked heads at the branch tips or less commonly axillary from the uppermost leaves. Heads radiate (discoid elsewhere). Involucre cup-shaped to slightly bell-shaped, the disc 5–12 mm in diameter, the bracts in 1 series. Involucral bracts 7–10, fused more than 2/3 of the way to the tip, with triangular teeth, the surface glabrous but dotted or lined with conspicuous, sessile, yellowish brown oil glands, somewhat thin and membranous, green but often pinkish- or purplish-tinged. Receptacle convex or somewhat conical, not or only slightly elongating as the fruits mature, with minute, irregular ridges around the attachment points of the florets. Ray florets 5–8 (commonly numerous in doubled horticultural forms), pistillate, showy, the corolla 10–30 mm long, relatively broad, yellow to orange, sometimes red or reddish brown toward the base. Disc florets 40–120, perfect, the corolla greenish yellow to orange, the tube slender, not expanded at the base nor persistent at fruiting, glabrous, the lobes sometimes hairy along the margins. Style branches with the sterile tip elongate and with a small, more or less spherical, expanded portion at the very tip. Pappus of 5–12 slender, unequal scales, these sometimes fused at the base, straw-colored or orangish brown, the margins irregular or more commonly with ascending barbs or teeth. Fruits linear to very narrowly wedge-shaped in outline, 4- or 5-angled and slightly flattened, the surface usually moderately pubescent with short, ascending hairs, especially along the angles, black. About 40 species, North America to South America; introduced in the Old World.

The two species of marigold in the Missouri flora are both escapes from cultivation and are sometimes difficult to differentiate (Neher, 1966). Some botanists have treated them as components of a single species. A third, very different, cultivated species of Tagetes is likely to be encountered in the future as an escape. Tagetes minuta L. (variously known as chinchilla, anisillo, tall khakiweed, Mexican marigold, and stinkweed, among other names) is widely grown as a seasoning for meats, soups, and vegetables. It is a densely branched annual with erect stems 30–100 cm long and pinnately dissected leaves. However, it differs from the other cultivated marigolds in Missouri in its more numerous heads with the slender, nearly cylindrical involucre 8–12 mm long, only 1–3 ray florets with inconspicuous corollas 1–2 mm long, only 3–5 disc florets, and somewhat shorter pappus and fruits.