Brooms form a tribe , Genisteae , of evergreen , semi-evergreen , and deciduous shrubs in the subfamily Faboideae of the legume family Fabaceae , mainly in the three genera Chamaecytisus , Cytisus and Genista , but also in many other small genera ( see box , right ) .
It is also the hardiest broom , tolerating temperatures down to about -25 ° C . The brooms belong to the subfamily Faboideae of the legume family Fabaceae , mainly in the three genera Chamaecytisus , Cytisus and Genista , but also in five other small genera ( see box , right ) .