Gorse(Ulex europaeus) is a spiny shrub that originates in the Mediterranean region of western Europe, but has been introduced to much of the world, and competes and often wipes out native plants. It does well on poor soils, and those where there have been multiple disturbances. It has virtually taken over some areas of the Pacific Northwest, and control of Gorse is becoming a major issue with landowners and government agencies. Gorse is very difficult to eradicate, as it cannot be killed by fire or cutting and the seeds remain viable for up to 40 years.

Gorse grows to about three meters tall in the Pacific Northwest. It has small grayish-green leaves and large spines. It produces masses of small pea-like yellow flowers in early spring that mature to black pods by summer. Gorse has deep roots and can survive in dry conditions, and creates a large amount of soil acidifying litter, which makes the ground too acidic for many competing plants.

One problem with Gorse is that the leaves contain large amounts of volatile oils, which make them extremely flammable. Gorse infestation is believed to have played an important role in the disastrous Tillamook Burn which destroyed over 240,000 acres in 1933, and the more recent Bandon Fires of the central Oregon coast.