White Spanish broom (Cytisus Albus) is a flowering shrub that's native to Portugal and parts of Spain. While pretty, it's considered invasive in Australia and California. It's still sold in some catalogs and nurseries as an ornamental landscape plant, but gardeners in warm areas (where this plant thrives) should be careful about adding it to their gardens.
White Spanish Broom
White Spanish broom grows readily from seed, and can reach four feet in height and width in about three years. It also blooms annually, producing large numbers of tiny whitish flowers. All of which is fine, but those flowers eventually turn into seed pods which burst, creating an explosive seed dispersal. Once this happens, if conditions are right in your garden, there's a good chance that you'll be trying to rid yourself of Cytisus seedlings for the foreseeable future.
White Spanish broom is hardy in Zones 8 through 10.
Dwarf Alpine Cytisus
Dwarf Alpine Cytisus (Cytisus Albus Ardoinii) is a low-trailing shrub that grows to four to six inches high. It is covered during April and May with deep yellow flowers, thriving in dry and sunny spots, its silky trifoliate leaves carried upon fine rod-like stems.
Silver-leaved Cytisus (Cytisus Albus Argenteus) has silvery leaves and grows well in very sunny, dry spots.
Austrian Cytisus (Cytisus Albus Austriacus) is a hardy variety from eastern Europe, growing as a compact leafy bush of two to four feet, bearing terminal clusters of yellow flowers during early summer and again in autumn.
Bean's Cytisus (Cytisus Albus Beanii) is a cross between Ardoinii and biflorus, which originated in the Royal Gardens, Kew. It is a dwarf, prostrate shrub, with the habit of Ardoinii, useful in masses for the rock garden, its yellow flowers appearing early in May.
Twin-flowered Cytisus (Cytisus Albus Biflorus) is the earliest of the Brooms. It grows to about four feet high. The bright yellow flowers appear in the axils of the leaves throughout the long shoots.
Cluster-flowered Cytisus (Cytisus Albus Capitatus) is a low, semi-evergreen shrub that prefers full sun to partial shade. It bears clusters of pale yellow flowers, at times shaded with bronze, at the tips of the long erect shoots. Though less showy than some kinds, its habit is neat and compact, and it flowers from the middle of July into autumn, when few sorts are in beauty.
Trailing Cytisus (Cytisus Albus Decumbens) is a dwarf, prostrate shrub from eastern Europe, with large pale yellow flowers in long erect spikes blooming from June till August, and perfect for rock gardens.
Italian Cytisus (Cytisus Albus Glabrescens) is a hardy plant from the mountains of northern Italy. It forms a small bush with golden flowers crowded in the axils of the leaves; these are deciduous, smooth above, and covered with soft hairs beneath.
Hairy Cytisus (Cytisus Albus Hirsutus) is a dwarf shrub one to two feet high, with trailing stems and yellow flowers in June and July. It's useful in the rock garden or the front line of shrub borders. The hairiness is only in the young growth, while the adult leaves are glossy and smooth.
Kew Cytisus (Cytisus Albus Kewensis) is a beautiful prostrate plant raised in Kew Gardens as a cross between Ardoinii and the White Broom, but distinct in habit from both parents. It spreads by long trailing shoots, rising only about three inches, but eventually spreading to a foot or more wide. Its creamy white or pale yellow flowers thickly cover the plant during May and June.
Summer-flowering Cytisus (Cytisus Albus Nigricans) has long slender shoots reaching six feet or more when full grown. Summer-flowering cytisus is hardy and thrives in dry, warm soil. The pale yellow flowers are borne in long erect spikes that grow to about nine inches long. It's easy to grow from seed sown indoors or directly in the garden.
Auvergne Broom (Cytisus Albus Purgans) is a shrub that reaches two to three feet tall. The yellow, fragrant flowers appear in April and May in most areas. This variety is easy to grow from seed sown indoors or directly in the garden in late fall.
Purple Cytisus (Cytisus Albus Purpureus) is a hardy plant from eastern Europe. It produces purple flowers from May until the first fall frost.
Schipka Cytisus (Cytisus Albus Schipkaensis) has a low spreading habit, flowering in a long succession from the end of June through most of the summer. The flowers are soft, yellowish-white, and grow in clusters.
Many-colored Cytisus (Cytisus Albus Versicolor) is a hybrid of purpureus and hirsutus. Its leaves and shoots are covered in velvety hairs, and its flowers, appearing in May, pass from creamy-white to rose and lilac, the several stages showing in the same cluster.
Plant With Care
While white Spanish broom is definitely a beautiful, interesting plant, it pays to consider whether it's something you want to contend with in your garden year after year. If you live in certain states (such as California) it may be illegal to grow this plant due to its invasive nature. There are plenty of rock garden plants that could be a better, non-invasive option.