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.

Source: Webster's Revised Unabridged Dictionary (1913)