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Plant Description


Rudbeckia hirta L.

En: black-eyed Susan, hairy coneflower
Fr: marguerite jaune, rudbeckie hérissée
Oj: mangishkiinzhigwe

Asteraceae (Daisy Family)

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Rudbeckia hirta1 Rudbeckia hirta2 Rudbeckia hirta3 Rudbeckia hirta4 Rudbeckia hirta5 Rudbeckia hirta6 Rudbeckia hirta7 Rudbeckia hirta8 Rudbeckia hirta9 Rudbeckia hirta10 Rudbeckia hirta11 Rudbeckia hirta12 Rudbeckia hirta13 Rudbeckia hirta14 Rudbeckia hirta15 Rudbeckia hirta16 Rudbeckia hirta17 Rudbeckia hirta18

Taxonomy: The only variety of black-eyed Susan native to Ontario is var. pulcherrima Farw., described below. Cultivated varieties of black-eyed Susan are usually present in commercial seed mixes used for rehabilitation, but may not be as hardy as plants grown from locally collected seed.

Synonym: Rudbeckia serotina Nutt.

General: A low perennial, arising from short taproots or fibrous roots; erect flowering stems are 2.5—7 dm tall. Flowering stems are unbranched, green to dark reddish-purple, and conspicuously hairy, with coarse spreading hairs (hirsute).

Leaves: Basal and stem (cauline) leaves are present; all are simple and coarsely hairy (hirsute). Basal leaves are long-petiolate, their blades are lanceolate, elliptic, or oblanceolate, 5—12.5 cm long by 1—2.5 cm wide. Stem leaves are alternate; leaves on the lower portion of the stem are spatulate and taper gradually to a narrow attenuate base, while upper stem leaves are smaller and sessile, with lanceolate to oblanceolate blades, 3—20 cm long by 0.5—4 cm wide; apices are blunt (obtuse) to pointed (acute), and margins are generally entire (rarely finely toothed).

Flowers: Plants in the Aster Family have flowers arranged in an inflorescences called a head (or capitulum), composed of few to many small flowers attached to a base (receptacle) covered with overlapping rows of bracts (phyllaries), which collectively form an involucre.

Single heads of black-eyed Susan flowers occur on erect, vertically ridged, and coarsely hairy (hispid) stalks (peduncles); flowering stems are terminal or few-branched at the leaf axils. Each head has 8—18 yellow ray flowers encircling the base of a domed receptacle, 1.2—2.2 cm tall by 1—2 cm wide, bearing 250—500+ minute purplish-brown disc flowers. Ray flowers are oblong to elliptic, 1.5—4.5 cm long by 0.5—1 cm wide, yellow to yellow-orange, often with a maroon spot near the base of each ray, or lighter yellow near the tips of each ray. Disc flowers are small, 3—4.2 mm long, and mature from the base of the receptacle upward; a ring of erect dark brown style branches, often coated in yellow pollen, indicates which disc flowers are in bloom. The involucre has 2-3 rows of overlapping lanceolate phyllaries, to 3 cm long, which are coarsely hairy (hispid). Flowers bloom in mid-summer.

Fruit: Small black achenes, 1.5—2.7 mm long, oblong, 4-angled, and flat (truncate) at the tip; pappus bristles are lacking.

Habitat and Range: Dry soils in disturbed areas, such as fields, clearings, along paths, roadsides, and open rights-of-way. Our local variety of black-eyed Susan (var. pulcherrima) is native to temperate eastern North America. In Canada, its native range extends from Nova Scotia to Saskatchewan, but it has also become naturalized in insular Newfoundland, Prince Edward Island, Alberta, and British Columbia. It is found throughout the Algoma District and extends north in Ontario to the Cochrane area.

Similar Species: The cutleaf coneflower (Rudbeckia laciniata L.) is native to the Algoma District, typically found in moist to wet rich habitats. This species has pinnately divided lower leaves with 3—7 lobes, glabrous to glaucous stems, and greenish yellow disc flowers on a receptacle that elongates at maturity.

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