Invasive Species: Fennel

Foeniculum vulgare

Fennel can become a problem due to its aggressive nature. It isn’t currently on the Oregon Noxious Weed List.

Why is it important to control?

Fennel can drastically alter the composition and structure of many plant communities, including grasslands, riparian, and wetland communities.

Fennel leaves, which are yellow-green and feathery.

How can you identify it?

A photo of fennel flowers on a brown background.A close up photo of fennel seeds.
Habitat: Sunny locations with well drained soil. Disturbed areas. Old fields, ditches, roadsides.
Life Cycle: Perennial
Height: Up to 10 ft
Leaf Description: Carrot-like finely-divided, feathery leaves
Fruit & Flower Description: Tiny yellow flowers form umbrella-shaped clusters about 4 in. across
Bloom Time: May to September

How do you control it?

  • Repeated slashing before flowering my kill smaller infestations.

  • For larger infestations, chemical methods are more effective.

How to Report it?

There are various ways you can report this noxious weed.

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