marsh marigold

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Any of several plants of the genus Caltha of the buttercup family, especially C. palustris, which grows in wetlands and has bright yellow flowers.

from The Century Dictionary.

• noun A golden-flowered plant, Caltha palustris: in the United States also called cowslip. See Caltha and gowan.

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

• (Bot.) A perennial plant of the genus Caltha (Caltha palustris), growing in wet places and bearing bright yellow flowers. In the United States it is used as a pot herb under the name of cowslip. See cowslip.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Caltha palustris, a perennial plant with bright yellow flowers.

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

• noun swamp plant of Europe and North America having bright yellow flowers resembling buttercups