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). All genera in this group are from the tribe Genisteae (syn. Cytiseae). These genera are all closely related and share similar characteristics of dense, slender green stems and very small leaves, adaptations to dry growing conditions. Most of the species have yellow flowers, but a few have white, orange, red, pink or purple flowers.