Vectors of Spread:
General: Gorse is a sizeable, evergreen spiky shrub that is considered noxious under BC’s Weed Control Act.
Flowers: Showy, pea-like, bright yellow flowers that grow in clusters at the end of branches. Flowers are 1.5 – 2 cm long.
Stem: Gorse grows in a single upright stem, which is heavily branched and grows to 1 – 3 m tall and up to 6 m wide. Stems are five-angled and sparsely hairy. Gorse plants grow outwards, forming a central area of dry, dead vegetation.
Leaves: Young plants have trifoliate leaflets, while mature plants have scales or spines. Spines are branched and grooved, 1.5 – 2.5 cm long. Gorse is dense and evergreen.
Seeds: Gorse produces black, hairy seedpods that are 1.5 – 2 cm long.
Roots: Are shallow with a deep taproot. As a member of the Pea family (Fabaceae), it forms nitrogen-fixing root nodules.
Scotch Broom (Cytisus scoparius) also has yellow pea-like flowers, but it has small, simple leaves rather than Gorse’s spine-like leaves.
St. John’s Wort (Hypericum perforatum) is a perennial that grows to about 1 m in height. It has showy, bright yellow flowers with 5 petals that turn rusty red when they mature. It prefers dry, sandy soils and full sun.
Spanish Broom (Spartium junceum) is another invasive Broom plant with yellow flowers. Like Scotch Broom, its leaves are round, unlike Gorse which has spine-like leaves. You can spot the difference between Spanish and Scotch Broom by their stems: Spanish Broom stems are round, whereas Scotch Broom stems are ridged. Spanish Broom also flowers later in the year.
Habitat and Origin
Gorse is native to Western Europe. It was first introduced as an ornamental in south coastal Oregon in the late 19th century, and has since spread widely in coastal areas from California to British Columbia.
Gorse thrives in poor, dry soils and high heat. It often becomes established on non-tillable land and inaccessible places like fence rows and river banks. Given its preference for sunny clearings, it is often found in sandy and rocky areas, roadsides, fields and pastures, bluffs, cutblocks, and cutbanks.
Propagation and Vectors of Spread
Gorse primarily reproduces by seed; one mature plant can produce up to 18,000 seeds annually, and seeds can remain viable in the soil for up to 40 years. Given the abundance of the seeds produced and their long-term viability, Gorse rapidly forms a seedbank in the soil. This is only compounded by the fact that it can live up to 45 years, with the first 15 being years of rapid growth. It can also reproduce vegetatively by cuttings.
Gorse’s exploding seedpods are a key element to its spread, as the seeds land several meters away from the parent plant. Seeds are also easily distributed by ants, animals and machinery. Since Gorse grows mainly by the ocean, water is a common carrier for seeds.
Economic and Ecological Impacts
- Creates impenetrable thickets that impede the movement of wildlife.
- Crowds out all other vegetation and releases toxins into the soil, causing a decrease in biodiversity, a loss of habitat and decreased forage for wildlife.
- Causes erosion, especially on steep slopes.
- Increases fire hazard, as Gorse contains volatile oils and produces large amounts of litter.
- Sharp thorns restrict recreational activities.
- Dense patches can hinder re-vegetation of harvested areas and recreational use of land.
- Increases cost of forestry practices.
What Can I Do?
Gorse is currently not found in the Sea to Sky, so PREVENTION of further spread is key.
Learn to identify Gorse: use the images presented in this profile page.
What to do if you spot it: You can report any Gorse sighting by clicking here.
- Regularly monitor properties for weed infestations.
- Ensure soil and gravel is uncontaminated before transport.
- Quickly re-vegetate disturbed areas with fast-growing competitive, native plants can limit growth of Gorse and is a fundamental tool to limit it.
- Minimize soil disturbance in area surrounding infestation.
- Ensure plants (particularly flowering heads or root fragments) are bagged or covered to prevent spread during transport to designated disposal sites (e.g. landfill).
- Remove plant material from any equipment, vehicles, or clothing used in infested areas and wash equipment and vehicles at designated cleaning sites before leaving the area.
- Do not plant Gorse in a garden, no matter how well-contained its enclosure may seem.
- Do not move soil that has been contaminated with Gorse.
- Do not mow or weed-whack Gorse plants, as the fragments can propagate as new colonies. Frequent mowing may also accelerate shoot development, leading plants to spread laterally from the parent plant.
- Hoeing or digging up small infestations, including all plant roots, may be effective.
- Re-sprouting can occur from any remaining root portions.
- Follow-up treatments to remove seedlings originating from root portions or from the seed bank will be required.
- Cutting plants alone is not effective to completely eradicate an infestation; herbicide must be applied to cut stumps.
- If you choose to mow Gorse, be prepared to do so repeatedly to deplete plant root reserves, as a single mowing will simply promote vegetative growth.
- Herbicide treatment is most effective after bloom drop.
- Glyphosate has been proven effective on growing plants, but the treatment should be followed by seeding or replanting at the site to prevent re-infestation from the seed bank.
- Selective herbicides such as dicamba, triclopyr, 2,4-D and metsulfuron are also effective and useful when an infestation is located within a grassed area.
- Triclopyr and glyphosate can also be applied in a variety of ways, including foliar application, basal cut stump, cut stump, and basal bark.
- Lastly, picloram is also effective to control Gorse, but it is not suitable for wet, coastal soils.
- We recommend that any herbicide application is carried out by a person holding a valid BC Pesticide Applicator Certificate. Before selecting and applying herbicides, you must review and follow herbicide labels and application rates; municipal, regional, provincial and federal laws and regulations; species-specific treatment recommendations, and site-specific goals and objectives.
There is no biocontrol available for Gorse in BC.
Coastal Invasive Species Committee, Gorse, https://www.coastalisc.com/gorse/
Electronic Atlas of the Flora of BC, Ulex europaeus, http://linnet.geog.ubc.ca/Atlas/Atlas.aspx?sciname=Ulex%20europaeus
Invasive Species Council of BC, Gorse, https://bcinvasives.ca/invasives/gorse/
Invasive Species Council of BC, Gorse TIPS Factsheet, https://bcinvasives.ca/wp-content/uploads/2021/01/Gorse_Factsheet_29_03_2019.pdf
King County Noxious Weed Control Program, Gorse, https://your.kingcounty.gov/dnrp/library/water-and-land/weeds/Brochures/Gorse_factsheet.pdf