Source : Webster's Revised Unabridged Dictionary (1913)

Laburnum \La*bur"num\, n. [L.] (Bot.)
   A small leguminous tree ({Cytisus Laburnum}), native of the
   Alps. The plant is reputed to be poisonous, esp. the bark and
   seeds. It has handsome racemes of yellow blossoms.

   Note: Scotch laburnum ({Cytisus alpinus}) is similar, but has
         smooth leaves; purple laburnum is {C. purpureus}.