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rudbeckia(rədbĕk`ēə): see black-eyed Susanblack-eyed Susan
or yellow daisy,
North American daisylike wildflower (Rudbeckia hirta) of the family Asteraceae (aster family) with yellow rays and a dark brown center. It is a weedy biennial or annual and grows in dry places.
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(coneflower), a genus of annual, biennial, or perennial herbs of the family Compositae. (The genus is sometimes combined with the genus Echinacea.) The stems are usually tall, and the leaves are entire or pinnatipartite to pinnatisect. The inflorescences are large heads. The torus, which initially is extremely convex and later becomes cylindrical, has sharp, scarious bracts. The ligulate flowers are fruitless and usually yellow or orange in color; the tubular flowers are bisexual, flower-bearing, and usually purple. The achenes have no pappus and sometimes have a small crown.
There are approximately 30 species, distributed in North America, primarily on the prairies. Many species are ornamentals. The most frequently cultivated species among the annual and biennial species are R. bicolor and the black-eyed Susan (R. hirta)—especially their varieties with combined yellow, purple, and brown ligulate flowers. Of the perennial species, the golden glow (R. laciniata)—especially its double-petal variety—is most frequently cultivated. The golden glow reaches a height of 1.5–2.5 m. Many new improved varieties, mainly hybrids of R. nitida and R. fulgida, are being raised.