Fucus spiralis (Spiral Wrack, Spiral Rockweed) is a brown seaweed with broad, flat, blades with a strong midrib. It differs from the more common Bladder Wrack (F. vesiculosos), in lacking air bladders and having twisted blades, with swollen receptacles at the tips, The plants are bushy and 100-300 mm tall. They grow on rocks in the upper intertidal, and are most common in inlets and estuaries. Its native range is from Iceland and Labrador to Morocco and Virginia. In 1959-1960 and later, they were found at many sites in British Columbia in Alaska. the genus Fucus is believed to have originated in the Pacific, so these occurrences were considered to be either remnants of native populations or early introductions form 19th century whaling and sealing. However, recent occurrences in Humboldt (1980-1994) and Tomales Bay (1994) are indicative of a recent introduction.