19.
Rudbeckia hirta
Linnaeus, Sp. Pl. 2: 907. 1753.
Black-eyed Susan
Annuals, biennials, or perennials,
to 100 cm (taprooted or roots fibrous).
Stems
hispid to hirsute (hairs spreading, 1+ mm).
Leaves:
blades elliptic, lanceolate, or ovate (not lobed), bases attenuate to cuneate, margins entire or serrate, apices acute, faces hispid to hirsute; basal petiolate, blades 8—30 × 0.5—7 cm; cauline petiolate or sessile, blades (sometimes pandurate) 3—20 × 0.4—4 cm.
Heads
borne singly or (2—5) in loose, corymbiform arrays.
Phyllaries
to 3 cm (faces hispid to hirsute).
Receptacles
hemispheric to ovoid; paleae 4—6 mm, apices acute, often attenuate, abaxial tips hirsute to hispid.
Ray florets
8—16; laminae (usually uniformly yellow to yellow-orange or with a basal maroon splotch, sometimes mostly maroon) elliptic to oblong or oblanceolate, 15—45 × 5—10 mm, abaxially hispid to hirsute.
Discs
12—22 × 10—20 mm.
Disc florets
250—500+; corollas proximally yellowish green, distally brown-purple, 3—4.2 mm; style branches ca. 1.5 mm, apices subulate.
Cypselae
1.5—2.7 mm;
pappi
0.
Varieties 4 (4 in the flora): e North America.
Some strains of
Rudbeckia hirta
are cultivated and/or used in seed mixes for "re-naturalization" and erosion control.