Rud·beck·i·a n.  Bot. A genus of composite plants, the coneflowers, consisting of perennial herbs with showy pedunculate heads, having a hemispherical involucre, sterile ray flowers, and a conical chaffy receptacle. There are about thirty species, exclusively North American. Rudbeckia hirta, the  black-eyed Susan, is a common weed in meadows.
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  Black-eyed Su·san. Bot. (a) The coneflower, or yellow daisy (Rudbeckia hirta). (b) The bladder ketmie.
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  Rudbeckia hirta
       n : the state flower of Maryland; of central and southeastern
           United States; having daisylike flowers with dark centers
           and yellow to orange rays [syn: black-eyed Susan, Rudbeckia
           serotina]