1. Eurybia furcata (E.S. Burgess) G.L. Nesom (forked aster)

Aster furcatus E.S. Burgess

Pl. 230 c, d; Map 976

Plants with long, sometimes relatively stout, fleshy rhizomes, sometimes forming dense colonies (but usually prevented from doing so by the nature of the rock ledge habitat). Stems 30–120 cm long, often slightly zigzag, sparsely to moderately pubescent with short, nonglandular hairs toward the tip, usually glabrous toward the base. Basal leaves often absent at flowering but lower stem leaves well developed, long-petiolate, the blade 4–15 cm long, heart-shaped to triangular-ovate, short-tapered at the tip, deeply cordate at the base, the margins sharply and usually coarsely toothed, the upper surface sparsely to moderately roughened-hairy with short, stiff, nonglandular hairs, the undersurface sparsely to moderately roughened-hairy with short, stiff, nonglandular hairs and usually also with softer, longer, curled, nonglandular hairs along the veins. Median and upper stem leaves gradually smaller, ovate to narrowly elliptic or narrowly lanceolate, rounded to angled or tapered at the base, the petioles becoming progressively shorter (the uppermost leaves often nearly sessile), slightly expanded at the base but not clasping the stem. Inflorescences flat-topped to somewhat dome-shaped panicles or clusters, the heads in loose to dense clusters or solitary at the branch tips, the branches sparsely to moderately pubescent with short, curved, nonglandular hairs. Involucre 7–10 mm long, the bracts in 4–7 strongly unequal, overlapping series, 1–2 mm wide and mostly 1.5–3.0 times as long as wide, narrowly lanceolate to oblong-lanceolate or narrowly oblong-ovate, rounded to bluntly pointed at the ascending tip, with a narrow (or sometimes absent), green central band toward the base (this sometimes somewhat keeled) and broad, relatively firm, pale yellowish margins, the green area much-broadened toward the tip, the margins otherwise appearing finely and densely hairy and sometimes dark purple or purplish-tinged, the outer surface moderately pubescent with fine, ascending, nonglandular hairs. Ray florets 12–20, the corollas 10–18 mm long, white, sometimes becoming pinkish- or lavender-tinged with age. Disc florets 25–40, the corollas 6–8 mm long, the lobes 0.8–1.2 mm long. Fruits 2.5–4.0 mm long, narrowly oblong-ellipsoid, usually somewhat flattened, with 8–12 ribs, sparsely to moderately pubescent with short, fine hairs. 2n=18. July–October.

Uncommon in portions of the Ozark and Ozark Border Divisions (Arkansas, Illinois, Indiana, Iowa, Michigan, Missouri, and Wisconsin). Bases and ledges of moist limestone and dolomite bluffs, and occasionally adjacent banks of streams.

This species is uncommon throughout its range and at one time was under consideration for protection under the federal Endangered Species Act. Genetic studies by Les et al. (1991) indicated that although the species is an obligate outcrosser, it has surprisingly low levels of overall genetic variation, which they interpreted to indicate that localized extirpations that reduced the amount of variation further might drive the species toward extinction. Steyermark noted that although forked aster is restricted to seepy, calcareous ledges and adjacent habitats in Missouri, farther north it is found in a larger variety of habitats.