Cytisus striatus is a species of flowering plant in the legume family known by the common names hairy-fruited broom[3] and Portuguese broom. This plant is native to the west of the Iberian Peninsula and northwestern Morocco.[4] It has been introduced and has become invasive in parts of western North America and other regions with Mediterranean-type climates [5].
This is a tall shrub often exceeding 2 metres (6.6ft) in height. It is highly branched and sprawling. The sparse leaves are made up of small leaflets about a centimeter long each. The shrub bears yellow legume flowers and the pods are covered in white hairs.
This shrub is similar to its relative, Cytisus scoparius, but it can be distinguished by the paler shade of yellow of its flowers and by the hairy coat on its pods.
The sead of this plant can be spread by ants. C. striatus is an upright, bushy shrub that can reach heights of 2-3 meters. It has green, photosynthetic stems with 8-10 longitudinal ridges and trifoliate or simple leaves that are deciduous or evergreen, depending on the climate. The yellow pea-like flowers occur singly or in pairs along the stems. The fruit is a slightly inflated, densely hairy legume pod that explosively releases seeds upon maturation [5].
Camponotus cf. Cruentatus on an open fruit of Cytisus striatus
This plant, beyond its native range, causes problems in many ways, including displacement of native species causing ecosystem degradation and loss, removing native plant food sources for wildlife, and a susceptibility to wildfire ignition and spread.
Outside its native range, Cytisus striatus can form dense, monospecific thickets that displace native vegetation, restrict wildlife movement, and substantially increase fire hazard due to high above-ground biomass and litter accumulation. In Portugal, dense broom stands have been reported to dominate roadsides and mountain slopes. These large fuel loads increase the risk of rural fires, which are difficult to control due to the shrub’s rapid regrowth. Researchers suggested converting biomass into pellets to prevent cutting or burning of valorize, which can reduce the wildfire risk and the cost of shrub clearing [6].
Field observations also show that C. striatus tends to proliferate near forest plantations and disturbed soils, suggesting that anthropogenic activity facilitates its persistence and spread.
In introduced regions such as the western United States, C. striatus readily colonizes open or disturbed habitats, particularly in Mediterranean-type climates. It competes with native plant communities and regenerates rapidly after fire or mechanical clearing. In California, broom species are classified as Class C pest plants by the California Department of Food and Agriculture (CDFA), while C. striatus and C. scoparius are further designated as List A invasive species by the California Invasive Plant Council (Cal-IPC), reflecting their aggressive spread and ecological impact [5].
Control strategies include manual and mechanical removal, herbicide application, and prescribed burning, though these are costly and require long-term maintenance to prevent re-establishment. Recent research has proposed that sustainable management could be supported through biomass utilization or bioactive compound extraction, creating economic incentives for removal while reducing ecological damage [5].
Potential applications include using residual materials for biomass pellets or torrefied biomass, which could also promote a circular economy. This study aims to characterize C. striatus biomass properties for potential pellet production and evaluate the resulting pellets against ENPlus quality standards. Initial tests involved shredding and drying the biomass to optimize particle size before pelletization, highlighting the need for proper processing techniques to ensure quality and efficiency in the biomass production [6].
Leonel Nunes' study on biomass properties for pellet production indicated lower-density chips compared to other species, raising concerns over their energy value [5].
Distribution and Habitat
The species is native to Portugal and Spain, extending into northern Morocco, where it forms part of shrubland ecosystems known as giestais. It typically grows in acidic, nutrient-poor soils from granite, schist, or quartzite. C. striatus is commonly found along roadsides, open hillsides, in forest clearings, fallow lands, and rocky slopes, often at elevations up to 1,200 meters [5].
In Portugal, C. striatus has become a dominant component of secondary vegetation communities following deforestation or fire disturbance [8]. Its rapid germination, nitrogen-fixing ability, and high seed output allow it to colonize disturbed soils efficiently. In North America, it is mostly found in California and Oregon, where its ecological behavior is similar to C. scoparius, establishing dense monocultures that alter soil composition and fire dynamics [5][6].
Due to its adaptability and nitrogen-fixing ability, it can dominate disturbed habitats and rapidly colonize open areas. The California Department of Food and Agriculture (CDFA) lists brooms as Class C pest species, while the California Exotic Plant Pest Council (CalEPPC) categorizes Scotch broom (Cytisus scoparius) and Portuguese broom (Cytisus striatus) as List A invasive species, reflecting their aggressive spread and ecological impact [5].
Ecology
As a member of the Fabaceae, C. striatus forms symbiotic nodules with Bradyrhizobium species that enable atmospheric nitrogen fixation. This improves soil fertility in poor or eroded areas [7]. Soils beneath the shrub typically contain higher concentrations of organic matter, nitrogen, and phosphorus than those in adjacent open areas [7].
C. striatus increases soil nutrient levels but reduces herbaceous species richness and diversity due to shading and competition. The shrub’s dense canopy can reduce understory herb diversity by creating shaded, nutrient-rich microsites dominated by grasses such as Poaceae and Asteraceae [7]. Despite this local suppression, the patchiness created by clumps increases overall landscape diversity.
Physiological studies show that C. striatus can alternate between atmospheric N2 fixation and inorganic nitrogen uptake, depending on phosphorus availability and soil fertility, thereby gaining a competitive advantage in low-nutrient environments. This flexibility enables the shrub to continue growing under sensitive conditions. C. striatus produces higher biomass at a low carbon cost and overcomes efficient nitrogen fixation under limited resources, contributing to its ability to thrive in degraded or acidic habitats [8].
Additionally, the species contributes to fire ecology by accumulating large amounts of combustible litter, which promotes high-intensity burns and further favors its regeneration [6]. Its extensive root system and resprouting ability allow quick post-fire recovery. This adds to C. striatus’ dominance in frequently disturbed landscapes.
Phytochemistry and Bioactive Compounds
Chemical analyses of flowers and fruits indicate significant nutritional and phytochemical value. The flowers contain approximately 21% protein, 18% fibre, and 2% lipids. The fruits contain 12% protein, 42% fibre, and 1% lipids. Both are rich in potassium, calcium, phosphorus, and magnesium, with no detectable cytotoxicity in cell assays [9].
Extracts from C. striatus contain isoflavonoids that act as antibiotic adjuvants against methicillin-resistant Staphylococcus aureus (MRSA). These compounds are only moderately antimicrobial on their own but enhance the activity of ciprofloxacin and erythromycin by interfering with bacterial resistance mechanisms [10].
The plant also exhibits antioxidant and anti-inflammatory properties attributed to its phenolic content, including flavonoids, saponins, and alkaloids [5].
Uses
Historically, Portuguese broom was used for thatching, broom-making, animal fodder, and as a soil improver due to its nitrogen-fixing capabilities [5]. Its flowers have been used in folk medicine for treating rheumatism, gout, hypotension, and liver disorders [9].
In modern research, the species has been tested for phytoremediation, particularly in soils contaminated with hexachlorocyclohexane (HCH) isomers. When inoculated with specific rhizobacterial strains, C. striatus demonstrated enhanced growth and pollutant degradation, suggesting potential for use in environmental cleanup [11].
This page is based on this Wikipedia article Text is available under the CC BY-SA 4.0 license; additional terms may apply. Images, videos and audio are available under their respective licenses.
