Gleditschia monosperma

from The Collaborative International Dictionary of English v.0.48

Locust tree \Lo"cust tree`\n. [Etymol. uncertain.] (Bot.)
   A large North American tree of the genus {Robinia} ({Robinia
   Pseudacacia}), producing large slender racemes of white,
   fragrant, papilionaceous flowers, and often cultivated as an
   ornamental tree. In England it is called {acacia}.
   [1913 Webster]

   Note: The name is also applied to other trees of different
         genera, especially to those of the genus {Hymen[ae]a},
         of which {Hymen[ae]a Courbaril} is a lofty, spreading
         tree of South America; also to the carob tree
         ({Ceratonia siliqua}), a tree growing in the
         Mediterranean region.
         [1913 Webster]

   {Honey locust tree} (Bot.), a tree of the genus {Gleditschia}
      ) {Gleditschia triacanthus}), having pinnate leaves and
      strong branching thorns; -- so called from a sweet pulp
      found between the seeds in the pods. Called also simply
      {honey locust}.

   {Water locust tree} (Bot.), a small swamp tree ({Gleditschia
      monosperma}), of the Southern United States.
      [1913 Webster]

from The Collaborative International Dictionary of English v.0.48

Water locust \Wa"ter lo"cust\ (Bot.)
   A thorny leguminous tree ({Gleditschia monosperma}) which
   grows in the swamps of the Mississippi valley.
   [1913 Webster]