High Quality Content by WIKIPEDIA articles! Postelsia, also known as the sea palm (not to be confused with the southern sea palm) or palm seaweed, is a genus of kelp. There is only one species, Postelsia palmaeformis. It is found along the western coast of North America, on rocky shores with constant waves. It is one of the few algae that can survive and remain erect out of the water; in fact it spends most of its life cycle exposed to the air. It is an annual, and edible, though harvesting of the alga is discouraged. Postelsia is a partially protected species in California.