flowers-of-an-hour

from the GNU version of the Collaborative International Dictionary of English.

• noun An annual weedy herb (Hibiscus trionum) with ephemeral yellow purple-eyed flowers, native to the Old World tropics and naturalized as a weed in North America.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun annual weedy herb with ephemeral yellow purple-eyed flowers; Old World tropics; naturalized as a weed in North America