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FNA | Family List | FNA Vol. 21 | Asteraceae | Rudbeckia

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.

1 Annuals, biennials, or perennials; stems branched at bases or proximal to or at or near mid heights, leafy mostly toward bases (leaves smaller distally); peduncles usually at least 1/2 plant heights (Gulf Coastal Plain, Florida to Texas)   (2)
+ Biennials or perennials; stems branched mostly beyond mid heights, leafy ± throughout; peduncles to 1/3 plant heights   (3)
2 (1) Stems branched mostly at or near mid heights; basal leaves oblanceolate, faces hispid to ± sericeous; Georgia to Texas   19a Rudbeckia hirta var. angustifolia
+ Stems branched at or near bases (plants often scapiform); basal leaves obovate to nearly orbiculate, faces scabrous to hirsute; c, s Florida   19b Rudbeckia hirta var. floridana
3 (1) Leaves: basal blades broadly ovate to broadly elliptic, 2.5–7 cm wide (lengths mostly 2 times widths), margins coarsely toothed; cauline (sometimes sessile) lanceolate, ovate, or pandurate (mostly Appalachian Highlands toIllinois)   19c Rudbeckia hirta var. hirta
+ Leaves: basal blades lanceolate to oblanceolate, 1–2.5(–5) cm wide (lengths 3–5 times widths), margins entire or serrulate; cauline blades spatulate, oblanceolate, or broadly linear   19d Rudbeckia hirta var. pulcherrima


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