2. Eurybia hemispherica (Alexander) G.L. Nesom (single-stemmed bog aster, southern prairie aster)

Aster hemisphericus Alexander

A. paludosus Aiton ssp. hemisphericus (Alexander) Cronquist

A. paludosus Aiton var. hemisphericus (Alexander) Waterf.

Heleastrum hemisphaericum (Alexander) Shinners

Pl. 229 c–e; Map 977

Plants with an often stout, woody rootstock and long, scaly rhizomes, sometimes forming loose colonies. Stems 12–120 cm long, usually not zigzag, glabrous or sparsely to moderately pubescent with short, nonglandular hairs toward the tip, glabrous toward the base. Basal leaves often absent at flowering, when present these and the lower stem leaves sessile or short-petiolate, the blade 2–10 cm long, linear to narrowly oblanceolate, angled or tapered to the usually sharply pointed tip, tapered at the base, relatively stiff and leathery, the margins entire but roughened with minute, stiff hairs, the surfaces glabrous, the upper surface often somewhat shiny. Largest leaves above the stem base, the median and upper stem leaves progressively smaller, linear, tapered at the base, sessile or nearly so, slightly expanded at the base and somewhat sheathing the stem. Inflorescences slender racemes, sometimes nearly spicate, sometimes appearing as few-branched, more or less elongate panicles with ascending spicate to racemose branches, occasionally reduced to a solitary terminal head, the stem or branches glabrous or sparsely to moderately pubescent with short, nonglandular hairs. Involucre 9–12 mm long, the bracts in 4–6 somewhat unequal to subequal, overlapping series, 1–2 mm wide and mostly 2–4 times as long as wide, narrowly lanceolate to oblong-lanceolate or narrowly oblong-ovate, sharply pointed at the loosely ascending to spreading or reflexed tip, with a narrow (or sometimes absent) central groove or midvein toward the mostly somewhat thickened base and broad, relatively firm, pale yellowish margins, the green area much-broadened abruptly toward the tip, the margins otherwise appearing minutely roughened or moderately short-hairy and sometimes dark purple or purplish-tinged, the outer surface glabrous. Ray florets 15–35, the corollas 10–25 mm long, purple to bluish purple. Disc florets 40–80(–95), the corollas 5.5–7.0 mm long, the lobes 0.7–1.2 mm long. Fruits 2.5–3.7 mm long, cylindrical or slightly wedge-shaped to narrowly oblong-ellipsoid, sometimes slightly flattened, with 9–16 ribs, glabrous or more commonly sparsely to moderately pubescent with short, fine hairs. 2n=18, 36. August–October.

Scattered in the Glaciated Plains Division and locally north and east to Callaway and Howell Counties; introduced in Marion County (Kansas to Texas east to Kentucky and Florida). Upland prairies and less commonly savannas and openings of dry upland forests; also pastures, railroads, and roadsides.

Steyermark (1963) and some other authors (Barkley, 1986) treated this taxon as a subspecies of the closely related E. paludosa (Aster paludosus). Cronquist (1980) noted that the two taxa (as A. paludosus and A. hemisphericus) were sometimes difficult to distinguish morphologically but were geographically distinct. Eurybia paludosa occurs along the Atlantic Coastal Plain from North Carolina to Florida, whereas E. hemispherica tends to be more of an inland plant. The also two differ in that the inflorescence of E. paludosa is flat-topped to hemispherical, the stems tend to be hairier (and often with slightly longer hairs) toward the tip, and the involucral bracts are less strongly thickened, with the margins tending to have slightly longer hairs.

Steyermark (1963) noted that this showy species deserved to be cultivated more widely as an ornamental wildflower. In recent years, it has become available through some of the state’s wildflower nurseries.