flower-of-an-hour

flower-of-an-hour
    n 1: annual weedy herb with ephemeral yellow purple-eyed
         flowers; Old World tropics; naturalized as a weed in North
         America [syn: {flower-of-an-hour}, {flowers-of-an-hour},
         {bladder ketmia}, {black-eyed Susan}, {Hibiscus trionum}]