The Collaborative International Dictionary of English v.0.48:

Nelumbo \Ne*lum"bo\, prop. n. [Ceylonese word.] (Bot.)
   A genus of great water lilies. The North American species is
   Nelumbo lutea, the Asiatic is the sacred lotus, Nelumbo
   speciosa. [Written also Nelumbium.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Yoncopin \Yon"co*pin\, n. [Perhaps corrupted from Illinois
   micoupena, Chippewa makopin, the American lotus.] (Bot.)
   A local name in parts of the Mississippi Valley for the
   American lotus (Nelumbo lutea).
   [1913 Webster]

WordNet (r) 3.0 (2006):

Nelumbo lutea
    n 1: water lily of eastern North America having pale yellow
         blossoms and edible globular nutlike seeds [syn: water
         chinquapin, American lotus, yanquapin, Nelumbo
         lutea]