(Science: botany) a small leguminous tree (Cytisus laburnum), native of the alps. The plant is reputed to be poisonous, especially. The bark and seeds. It has handsome racemes of yellow blossoms.
Scotch laburnum (Cytisus alpinus) is similar, but has smooth leaves; purple laburnum is c. Purpureus.
One of its medicinal uses is a source of cystisine, which is marketed as non-nicotine drug for smokers who want to quit.