Branched holdfast holds a single thallus to 4-6 cm in height and about 4-6 mm in diameter flattening abruptly to a single blade. Greenish to dark brown unbranched blade can reach up to 5 m in length and is covered with small wrinkled depressions. SAMPLING CODE NOTES: LABL = Blade; LAFA = Adult >= 10 cm wide blade; LAFR = Recruit < 10 cm wide blade; LAHO = Holdfast.

Common, perennial, fertile in late summer.

Subtidal to 50 m; British Columbia, Canada to Baja California Mexico.