1. Astranthium ciliatum (Raf.) G.L. Nesom

A. integrifolium (Michx.) Nutt. var. ciliatum (Raf.) Larsen

A. integrifolium ssp. ciliatum (Raf.) DeJong

Pl. 229 h, i; Map 962

Plants annual, usually relatively slender, with sometimes short taproots. Stems 1 or few, 5–45 cm long, erect or ascending, unbranched or with few to several ascending branches above the midpoint, often 4–6-angled, sparsely to moderately pubescent (especially along the ridges) with strongly to loosely ascending white hairs. Basal leaves sometimes withered by flowering time, 1.5–5.0 cm long, 0.3–1.2 cm wide, the blade oblanceolate to obovate or spatulate, rounded to bluntly pointed at the tip, long-tapered to the mostly short-petiolate base, the margins entire (rarely slightly wavy or scalloped), the surfaces and especially the margins sparsely to more commonly moderately hairy. Stem leaves often somewhat reduced above the lower portion of the stem, 0.5–5.0 cm long, rounded to bluntly or sharply pointed at the tip, more or less tapered to a slightly expanded but not strongly clasping base, the margins entire, the surfaces and especially the margins sparsely to moderately hairy. Inflorescences of solitary heads at the branch tips, these relatively long, bractless or nearly so. Heads radiate, not sticky or resinous. Involucre 2.5–4.5 mm long, cup-shaped to slightly bell-shaped. Involucral bracts in 2 similar to slightly unequal, overlapping series, lanceolate to elliptic or narrowly ovate, the tip ascending, with a relatively broad, green central stripe and broad, thin, pale (often somewhat transparent) margins, glabrous or sparsely hairy. Receptacle hemispherical to conical, with minute, irregular ridges around the concave attachment points of the florets. Ray florets 13–25, pistillate, the corolla 6–12 mm long, white, sometimes purplish-tinged on the undersurface, usually turning purple to purplish blue with age, not persistent at fruiting. Disc florets numerous (usually 120–170), perfect, the corolla 2–3 mm long, yellow, not persistent at fruiting. Pappus of the ray and disc florets essentially absent, represented by a faint line or minute ridge. Fruits 1.0–1.6 mm long, more or less obovoid, somewhat flattened, the angles more or less rounded or slightly ribbed, the surface smooth, usually sparsely to moderately pubescent with minute hairs, the hairs often slightly curved toward the midpoint but straight at the tip, tan to greenish brown or dark brown. 2n=8. April–June.

Uncommon in the southwestern portion of the Ozark Division (Missouri and Kansas south to Texas; Mexico). Chert, limestone, and dolomite glades, ledges and tops of bluffs, thin-soiled areas in upland prairies, savannas, and banks of streams and rivers.

DeJong (1965) accepted two taxa within A. integrifolium. He characterized ssp. integrifolium as having fibrous roots, longer achenes (1.6–2.2 mm) with sparser hairs, slightly larger heads (involucre 4–6 mm long) and corollas (disc corollas 2.0–3.2 mm, ray corollas 12–15 mm), and a generally more western distribution (Kentucky to Georgia west to Missouri and Arkansas). DeJong indicated that both of his subspecies were present in Missouri but annotated most of the Missouri specimens as representing intermediates or hybrids between the two subspecies. Yatskievych and Turner (1990) erroneously listed only ssp. integrifolium for Missouri. In fact, most of the specimens in question seem to represent ssp. ciliatum, even by DeJong’s criteria. Nesom (2005) refined the taxon limits slightly and raised ssp. ciliatum to species level, while maintaining that the number of intermediate specimens in the region of contact with A. integrifolium in the strict sense was many fewer than earlier reports had suggested. Nesom’s circumscription of taxa is accepted in the present treatment, which results in the exclusion of true A. integrifolium from the Missouri flora.