1. Ratibida columnifera (Nutt.) Wooton & Standl. (longhead prairie coneflower, Mexican hat)

R. columnaris Pursh

Pl. 286 a, b; Map 1214

Plants with a taproot. Stems 30–60(–100) cm long, solitary or clustered. Leaf blades 2–15 cm long, mostly oblong-elliptic to oblong-obovate in outline, 1 or 2 times deeply pinnately divided, the divisions 3–15, 0.1–6.0 cm long, linear to narrowly oblong or oblong-oblanceolate, with 1 inconspicuous vein. Heads positioned mostly well above the leaves, the stalks to 45 cm long. Involucral bracts 5–14, those of the outer series 4–15 mm long, linear, those of the inner series 1–3 mm long, mostly narrowly ovate. Receptacle columnar, 1–5(–7) cm long. Ray florets 4–11, the corolla (8–)10–35 mm long, yellow or less commonly with a well-defined zone of reddish brown to brownish purple toward the base, this occasionally entirely masking the yellow coloration, the outer surface moderately to densely but inconspicuously short-hairy, both surfaces usually with scattered, minute, sessile, spherical, yellow glands. Disc florets numerous, the corolla 1.5–2.5 mm long, yellow to yellowish green, sometimes purplish-tinged toward the tip. Style branches with the sterile tip short and blunt. Pappus of 1 or 2 minute, triangular, brownish teeth. Fruits 1.5–3.0 mm long, somewhat obliquely oblong, the tip and the angle opposite the chaffy bract with a minute, orangish brown fringe. 2n=28. June–September.

Possibly introduced, widely scattered, mostly in the western half of the state (Idaho to Arizona east to Minnesota and Louisiana; Canada, Mexico; introduced elsewhere nearly throughout the U.S.). Upland prairies; also pastures, railroads, roadsides, and open, disturbed areas.

The native status of R. columnifera in Missouri is questionable. Steyermark (1963) treated the species as native at least at some sites in Missouri. Earlier, however, Palmer and Steyermark (1935) had stated, “Generally and perhaps everywhere introduced from farther west.” Nearly all of the herbarium specimens, even those from the western portion of the state, are indicated on their labels as representing introduced plants. The few occurrences at upland prairie sites are from remnant prairies adjacent to roads or railroads. A complicating factor has been that the species sometimes is a component of wildflower seed mixes sown along public roadways for roadside beautification, which has increased the spread and abundance of R. columnifera in recent years. On the other hand, Missouri is contiguous with the main portion of the species range, and the species has been noted as a native colonizer of disturbed habitats.

Uncommon plants with the ray corollas entirely or partially reddish brown to brownish purple have been called f. pulcherrima (DC.) Fernald.