1. Palafoxia callosa (Nutt.) Torr. & A. Gray

Pl. 284 i–k; Map 1209

Plants annual, with taproots. Stems 15–60 cm long, erect or ascending, few- to several-branched, with fine longitudinal ridges and grooves, sparsely to densely pubescent with short, stiff, ascending hairs, these replaced abruptly with dark, tack-shaped glands toward the tip. Leaves alternate, sessile or the largest leaves with a short, poorly differentiated petiole. Leaf blades 2–7 cm long, linear, relatively thick (the smaller leaves often nearly as thick as wide), unlobed, the margins entire and on the largest leaves sometimes curled under, tapered at the base, tapered or narrowed to a sharply pointed tip, the surfaces sparsely to densely roughened-pubescent with short, loosely appressed, pustular-based hairs, the bases sometimes conspicuously darkened. Inflorescences open, more or less flat-topped panicles with short, leaflike bracts at the branch points, the branches with moderate to dense, dark, tack-shaped glands, the heads usually solitary and long-stalked at the branch tips. Heads discoid. Involucre 3–6 mm long, 2–5 mm in diameter, conical, the bracts in 2 subequal series. Involucral bracts 9–12, linear, ascending at the tip, the outer surface and margins moderately pubescent with short, white, appressed hairs and/or dark, more or less tack-shaped glands. Receptacle flat, not elongating as the fruits mature, naked. Disc florets 5–30, perfect, the corolla 5–6 mm long, pink to purplish pink (rarely white elsewhere) above the slender, slightly darker purple tube, the tube not expanded at the base or persistent at fruiting, usually sparsely hairy, the minute, abruptly expanded throat and the relatively long, slender lobes mostly glabrous. Style branches with the sterile tip elongate and tapered to a usually sharply pointed tip. Pappus of usually 8 scales, these 0.3–1.0 mm long, oblanceolate to obovate, papery, straw-colored. Fruits 3–5 mm long, narrowly wedge-shaped in outline, strongly 4-angled, the surface otherwise smooth, moderately pubescent with fine, appressed-ascending hairs (these sometimes produced in fascicles of 2 or 3 hairs), purplish black to black, dull or slightly shiny. 2n=20. August–October.

Scattered in the southwestern portion of the Ozark Division and introduced sporadically farther north and east (Missouri south to Texas and Mississippi; Mexico). Glades and tops of bluffs on calcareous substrates, less commonly banks of streams and rivers; also quarries, roadsides, and dry, open, disturbed areas.

Steyermark (1963) noted that this attractive annual performed well in a sunny portion of his garden.