7.
Rudbeckia laciniata
Linnaeus, Sp. Pl. 2: 906. 1753.
Cutleaf coneflower
Perennials,
50—300 cm (rhizomes often elongate, slender, plants colonial, roots fibrous).
Leaves
green, blades broadly ovate to lanceolate, all but distalmost 1—2-pinnatifid or pinnately compound, leaflets/lobes 3—11, bases cuneate to attenuate or cordate, margins entire or dentate, apices acute to acuminate, faces glabrous or hairy (sometimes with translucent patches); basal (often withering before flowering) petiolate, 15—50 × 10—25 cm; cauline petiolate or sessile, mostly lobed to pinnatifid, sometimes not lobed, 8—40 × 3—20 cm.
Heads
(2—25) in loose, corymbiform arrays.
Phyllaries
to 2 cm (8—15, ovate to lanceolate, margins mostly ciliate, glabrous or hairy).
Receptacles
hemispheric or ovoid to globose; paleae 3—7 mm, apices (at least of proximal) truncate or rounded, abaxial tips densely hairy.
Ray florets
8—12; laminae elliptic to oblanceolate, 15—50 × 4—14 mm, abaxially hairy.
Discs
9—30 × 10—23 mm.
Disc florets
150—300+; corollas yellow to yellowish green (lobes yellow), 3.5—5 mm; style branches 1—1.5 mm, apices acute to rounded.
Cypselae
3—4.5 mm;
pappi
coroniform or of 4 scales, to 1.5 mm.
Varieties 5 (5 in the flora): North America.
Cultivars of
Rudbeckia laciniata
are grown as ornamentals. The cultivar 'golden-glow' is widely planted and occasionally escapes cultivation. Among the varieties traditionally recognized in floristic treatments, vars.
ampla
and
heterophylla
are the most distinctive. Detailed investigation may show that the other varieties, from eastern North America, represent broadly intergrading forms that should be subsumed under var.
laciniata
.
