Flaveria campestris Johnston

Flaveria campestris is distinguished by subglomerulate capitulescences with 5–6(–8) florets per head, subtended by 3 leafy bracts, keeled phyllaries, and linear-lanceolate leaves with serrate or spinulose-serrate margins, and its distribution. The prevalence of F. campestris fluctuates greatly from year to year, generally depending on the existence of wet, saline habitat.

Annuals, 18–70(–90) cm (delicate or robust, mostly glabrous). Stems usually erect (tufted-pubescent at nodes). Leaves sessile; blades linear-lanceolate to lanceolate, 30–90 × 6–22 mm, bases barely connate, margins strongly to weakly serrate or spinulose-serrate. Heads (10–)15–100+, in tight subglomerules in corymbiform arrays. Calyculi of 2 linear-lanceolate bractlets 1–3 mm. Involucres urceolate or oblong, 6–7 mm. Phyllaries 3, elliptic, obovate, or oblong-obovate. Ray florets 0 or 1; laminae yellow, ovate, 1.5–2.5 mm (apices notched). Disc florets 5–6(–8); corolla tubes 0.8–1.3 mm, throats funnelform, 1.2–1.7 mm. Cypselae oblanceolate, linear, or oblong, 2.8–3.6 mm (those of rays longer by ca. 0.2 mm); pappi 0. 2n = 36 (18).

Flaveria campestris J. R. Johnston, Proc. Am. Acad. 39: 287
1903.
Flaveria angustifolia A. Gray (Mem. Am. Acad. II. 4: 88, hvponym. 1849); Coult. Contr. U. S. Nat. Herb. 2: 234. 1892. Not F. angustifolia Pers. 1807.
A dichotomously branched herb; stem erect, glabrous, or pubescent only at the nodes; leaves linear or linear-lanceolate, serrulate, 3-ribbed, narrowed at the base, slightly connate, 2.5-7 cm. long, 1-2.5 cm. wide; inflorescence densely cymose; heads 4-5-flowered; involucral bracts 3, nearly equal, 5 mm. long, the calyculate ones 2, unequal, 1-3 mm. long, linear-lanceolate; ligule oval, reflexed, 2.5 mm. long; disk-flowers 3-4; corollas 3 mm. long; tube slightly villous, fully equaling the funnelform throat; aehenes 2.5-3 mm. long, that of the ray slightly larger than the rest.
Type locality: (Type not designated, but the first specimen cited was from Courtney, Missouri.)
Distribution: Missouri to Colorado. New Mexico, and Texas.

Flaveria campestris, common name alkali yellowtops, is a plant species native to the southwestern United States and to the southern Great Plains (Arizona, Utah, New Mexico, Colorado, Texas, Missouri, Kansas, Oklahoma). It is found on saline soils and on the margins of lakes, ponds and streams.

Flaveria campestris is an annal herb up to 90 cm (3 feet) tall. It produces a tightly packed corymb of up to 100 small flower heads. Flowers are yellow, sometimes lacking ray flowers, other times with only a single ray flower per head. Each head has 5-8 disc flowers.

Flaveria campestris là một loài thực vật có hoa trong họ Cúc. Loài này được I.M.Johnst. mô tả khoa học đầu tiên năm 1903.