- Kingdom: Plantae
- Phylum: Ochrophyta
- Class: Ulvophyceae
- Order: Fucales
- Family: Fucaceae
- Scientific name: Fucus serratus
- Norwegian: sagtang
This brown seaweed is also known as serrated wrack, obviously from the serrated edge of the fronds. The fronds are flat, 1-3 cm wide and up to one meter long. It branches irregularly. It does not have any bladders. The entire plant may grow to a height of almost 2 meters. The color is olive-brown.
It is common in lower tidal and subtidal zones.
It is distributed on both sides of the North Atlantic Ocean, as far south as the Canary Islands.