Description: Thallus of this golden to medium brown kelp has a flat blade that can be slightly undulate at the margin; stipe to ~15 cm long. The holdfast is discoidal. This slow-growing kelp often displays several years of growth, denoted by the constrictions between roundish blade segments. A blade 7 years old can be less than 1 meter (39 in) long. Habitat: This perennial kelp occurs on rock in the shallow subtidal. Similar taxa: Laminaria yezoensis also has a discoid holdfast, but it does not occur in the Arctic