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.