Memorial Day closure

Most City of Portland offices will be closed Monday, May 27, in observance of Memorial Day.

Invasive Plant: Gorse

Photo shows shrub with bright yellow flowers.
Gorse infestations are mainly found in Oregon’s southwestern coastal counties. No patches are known in Portland yet, but small patches have been found in the counties around Portland.
On this page

 At a Glance

  • Scientific name: Ulex europaeus
  • Annual, perennial, or biennial? Perennial, evergreen shrub
  • Conditions it likes best: Mix of sun and shade
  • How it spreads: Seeds
  • How it causes damage: Forms dense thickets that prevent other plants from getting water and light, which leads to fewer kinds of plants. Fewer kinds of plants then leads to fewer kinds of animals. Greatest damage is to forests and pastures. Gorse is very expensive to completely remove. Seeds can sprout even after many years in the soil. Gorse also burns very quickly, making wildfires more difficult to put out.
  • Best time and way to manage: Gorse is not found in Portland.
  • Oregon Department of Agriculture noxious weed rank: B
  • Report patches of this plant? Yes. Oregon law requires that you report all sightings immediately for assistance. Use the online tool at Oregon Invasives Hotline or call 866-INVADER to let the state know when and where you found this plant. You may also contact Environmental Services (contact information on this page), who will notify the state of Oregon for you and help you remove these plants. A photo and location are required.

How to Identify Gorse

Photo shows plant with thorns and yellow flowers
Gorse is on the Required Eradication List. Photos by Glenn Miller, Oregon Department of Agriculture

Gorse often starts growing on land that’s hard to farm, like along fences or streambanks. Gorse are tough shrubs with long, stiff spines instead of typical leaves. The spines are 0.5-inch to 1.5-inches inches long and stay green all year.

Fall-Winter. The long spines make gorse easy to identify, although flowers may also be present all year. 

Spring. Gorse has the most flowers between March and May. Their yellow flowers look a lot like Scotch broom flowers. 

Summer. In early summer, flowers turn into brown, hairy seedpods that explode when they are dry.

How and When to Remove Gorse

Gorse is not found within the city of Portland, but it has been found in counties around Portland. It is on the state’s target list, so all patches must be reported and removed.

  • Requires professional management. Gorse is a high priority plant and would be managed by professionals from the City or the State. This plant is on Oregon’s and Portland’s Required Eradication List, so it is important to report any plants found so they can be removed.
  • Check. Check the site for new plants at least once a year, and especially for the first 2-3 years after removal..
  • Replant. After a year or two of managing this plant, consider planting native or less aggressive non-native plants.

Prevention is Best Practice

Clean your boots, pets, and maybe even your tires when you finish a hike or trail ride in Pacific Northwest natural areas, or if you have invasive plants on your own property. Cleaning boots and pets keeps invasive plants from spreading to new places. Be careful when trading plants with neighbors and fellow gardeners to make sure you’re not trading this or any other plant of concern.

Properly Dispose of Invasive Plants

To prevent spreading invasive plants:

  • Never place plants or seeds in your compost or yard debris.
  • Never throw pulled plants on the ground or into the street or sidewalk.
  • Put all pulled plants, bulbs, or seeds into a plastic bag and put the bag in the trash.
  • Wash all garden tools and gloves.