3. Eurybia macrophylla (L.) Cass. (large-leaved aster)

Aster macrophyllus L.

Pl. 230 a, b; Map 978

Plants with long, sometimes relatively stout, fleshy rhizomes, often forming large colonies. Stems 30–120 cm long, often slightly zigzag, moderately to densely pubescent with short, gland-tipped hairs toward the tip, sparsely glandular to nearly glabrous toward the base. Basal and lower stem leaves present, long-petiolate, the blade 5–25 cm long, heart-shaped to irregularly ovate, short-tapered at the tip, deeply cordate at the base, the margins sharply toothed, the upper surface usually sparsely to moderately roughened-hairy with short, stiff, nonglandular hairs (rarely also sparsely glandular), the undersurface sparsely to moderately pubescent with a mixture of gland-tipped and nonglandular hairs, sometimes nearly glabrous. Median and upper stem leaves progressively smaller, ovate to elliptic, truncate to tapered at the base, the petioles becoming progressively shorter and more broadly winged, slightly expanded at the base and sometimes somewhat clasping the stem. Inflorescences flat-topped to somewhat dome-shaped panicles or clusters, the heads in loose to dense clusters or less commonly solitary at the branch tips, the branches moderately to densely pubescent with short, gland-tipped hairs. Involucre 7–11 mm long, the bracts in 5–7 strongly unequal, overlapping series, 1–2 mm wide and mostly 1.5–3.0 times as long as wide, oblong-lanceolate to 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 abruptly much-broadened toward the tip, the margins otherwise appearing uneven or finely hairy and sometimes dark purple or purplish-tinged, the outer surface glabrous or more commonly moderately to densely pubescent with a mixture of gland-tipped and nonglandular hairs. Ray florets 9–20, the corollas 8–15 mm long, usually lavender to purple, rarely white. Disc florets 20–40, the corollas 6–8 mm long, the lobes 1.0–1.5 mm long. Fruits 2.5–4.5 mm long, narrowly oblong-ellipsoid, usually somewhat flattened, with 7–12 ribs, glabrous or sparsely hairy toward the tip. 2n=72. August–October.

Uncommon, known thus far only from Howell, Madison, Shannon, and Texas Counties (eastern [mostly northeastern] U.S. west to Minnesota and Missouri; Canada; introduced in Europe). Ledges and tops of bluffs and mesic upland forests on steep slopes, rarely banks of streams.

This species was first reported for Missouri by Summers and Yatskievych (1990). The earliest Missouri specimens were collected in 1970 by the late Art Christ but initially were misdetermined. This may have been because the somewhat disjunct Ozarkian populations usually produce few flowering stems in any given year, existing mostly vegetatively as large colonies of basal rosettes.