Thin-Leaved Coneflower (Rudbeckia triloba)
Very similar to its cousin the Black-Eyed Susan (R. hirta), but note the branching habit and the smaller flower heads with shorter, rounder rays. These plants grew in a sunny meadow in Sewickley Heights, where they were blooming in late August.
Flowers. Heads with large, conical or hemispherical brown disk; about 8 short, elliptical golden rays.
Leaves. Rough; upper sessile, with shallow teeth, ovate, pointed; lower often with 3 irregular lobes.
Stem. Rough-hairy, purple; frequently branching; about 3 feet (1 m) high.
Gray describes the genus and the species:
RUDBÉCKIA L. CONE-FLOWER. Heads many-flowered, radiate; the rays neutral. Bracts of the involucre leaf-like, in about 2 rows, spreading. Receptacle conical or column ir ; the short chaff concave, not rigid. Achenes 4-angled (in our species), smooth, not margined, flat at the top, with no pappus, or a minute crown-like border. — Chiefly perennial herbs, with alternate leaves, and showy terminal heads; the rays generally long, yellow, often darker at base. (Named in honor of the Professors Rudbeck, father and son, predecessors of Linnaeus at Upsal.)
Achenes annular; chaff persisting in age.
Disk hemispherical to ellipsoid-ovoid in fruit, dark purple or brown.
Lower leaves 3-lobed or parted.
R. triloba L. Hairy, biennial, much branched, 0.5-1.6 m. high; branches slender and spreading; upper leaves ovate-lanceolate, sparingly toothed; lower 3-lobed, tapering at base, ooarsely serrate (those from the base pinnately parted or undivided); rays 8-10, oval or oblong; chaff of the black-purple depressed-globular disk smooth, awned. — Rich soil, N. J. to Minn., Kan., and southw.; escaped from cultivation further northeastw. July, Aug. — Heads small, but numerous and showy.