Postelsia palmaeformis, also known as the sea palm (not to be confused with the southern sea palm) or palm seaweed, is a species of kelp and classified within brown algae. It is the only known species in the genus Postelsia. The sea palm 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 due to the species' sensitivity to overharvesting. History The sea palm was known by the natives of California by the name of kakgunu-chale before any Europeans entered the region. Postelsia was first scientifically described by Franz Josef Ruprecht (1814–1870) in 1852 from a specimen found near Bodega Bay in California. Ruprecht, an Austro-Hungarian who became curator of botany at the Academy of Sciences in St. Petersburg in 1839, studied seaweed specimens collected by botanist Ilya Vosnesensky, and published a paper describing one seagrass and five seaweeds, one of which was Postelsia. The sea palm has been used by several textbooks, such as the Campbell–Reece Biology textbook, as an example of multicellular protists, as well as an example of the class Phaeophyceae. Etymology The generic name, Postelsia honors Alexander Philipov Postels, an Estonian-born geologist and artist who worked with Ruprecht, while the specific name, palmaeformis, describes the alga's superficial similarity in appearance to true palms. Fossil record Fossils from Monte Bolca, a lagerstätte near Verona, were originally named Zoophycos caput-medusae and previously thought to be trace fossils, but were later found to be plants instead and given the name Algarum by French zoologist Henri Milne-Edwards in 1866. The type specimen collected by Italian paleobotanist Abramo Bartolommeo Massalongo before 1855 is at the Natural History Museum of Verona and was preserved in a lithographic limestone upper and lower slab. When Italian botanist Achille Forti (1878–1937) worked on the specimens in 1926, they were reinterpreted as close relatives of Postelsia, now known to be a brown algae, which had lived in the coastal waters of the Eocene sea. Forti renamed the species Postelsiopsis caput-medusae commemorating the fossils' extreme similarity to the extant Postelsia palmaeformis. The appearance of the plant fossil is a holdfast on the bottom, with a stem-like stipe between there