The term “broom tree” is not the official name for a single species, but rather a common designation applied to several species of woody shrubs and small trees recognized for their long, flexible branches. These plants belong to the pea family and are often found in dry, open habitats across the world, though they are native to Europe and the Mediterranean. The ambiguity of the common name stems from the plants’ historical use and a shared physical resemblance across different genera. Understanding this common name requires looking at the specific botanical identities that fit this description, which are mostly known simply as “broom.”
Clarifying the Plant’s Identity
The plants most commonly referred to as “broom” or “broom tree” fall into the legume family, Fabaceae, and are primarily members of the genera Cytisus, Genista, and Retama. The most widely known species is Scotch Broom, scientifically named Cytisus scoparius, which is a deciduous shrub native to western and central Europe. This plant typically grows to a height of 4 to 8 feet, forming a bushy, rounded crown.
Other species also carry the broom designation, such as the White Weeping Broom (Retama raetam), a desert shrub prominent in the Judean wilderness and Sinai Peninsula. While many brooms are shrubs, some species, like the one sometimes called “fragrant broom,” can achieve a taller, more tree-like form in certain environments, reaching up to 10 feet. The primary candidates share the characteristic of having tough, slender stems, which is the physical trait that gave them their common name.
Unique Physical Characteristics
A distinguishing feature of these plants is their green, ridged stems, which are often photosynthetic, taking over the role of leaves. The green shoots of Cytisus scoparius have a somewhat “twizzler stick” appearance and are arching and twiggy. Leaves on these plants are typically small, simple, or trifoliate with three leaflets, and often fall off early in the plant’s life or during periods of stress.
The flowers of broom plants are distinctly pea-like, a trait shared by the entire Fabaceae family. Scotch Broom is known for its profuse, golden-yellow blooms that appear in late spring, sometimes with red or pink hues in cultivated varieties. White Weeping Broom, conversely, produces small clusters of white to pink flowers. The fruit is a flat or oblong legume, or seed pod, which turns black as it matures. In many species, including Scotch Broom, the seed pods dry out and burst open with an audible sound, forcibly scattering seeds several feet from the parent plant.
Traditional Function and Environmental Status
The common name “broom” originates from the historical practice of bundling the plant’s long, flexible, and sturdy stems to create brushes and brooms. The branches were also used for thatching roofs, weaving baskets, and as a source of fiber for cloth and paper. Historically, the plant had medicinal uses; for instance, the young shoots were used as a diuretic and cardiac stimulant due to the presence of sparteine.
Many broom species contain toxic alkaloids that can affect the heart and nervous system. Ecologically, many brooms are successful colonizers because they are legumes, meaning they can fix nitrogen in the soil, allowing them to thrive in poor or disturbed ground. This ability, combined with prolific seed production and a long-lived seedbank, has resulted in several species, especially Scotch Broom, being designated as aggressive invasive species in non-native habitats like North America and Australia. They often form dense, pure stands that crowd out native flora and increase the risk of wildfires.