UC has emphasized marine algae from its inception, primarily due to the interests of its founder, W.A. Setchell, who specialized in several groups of seaweeds and in marine biogeography. As a result of Setchell's efforts and those of his successors, G.F. Papenfuss and P.C. Silva, UC's seaweed collection is exemplary. Over the years, it has developed an emphasis on Pacific Coast algae, beginning with Setchell's unrealized goal of producing a seaweed flora of the Pacific Coast.

When Setchell arrived in 1895, he inherited a small collection of seaweeds collected by Marshall Avery Howe from Monterey Bay. Setchell collected extensively with the help of amateurs and the collections grew in size and geographic scope. Setchell procured a large number of type specimens and established contacts worldwide. His students, including Nathaniel Lyon Gardner, became well known phycologists. One of Setchell's earliest accomplishments was the Phycotheca Boreali-Americana, the Algae of North America. This 46 volume set of exsiccatae, including many type specimens, was distributed in 80 sets to major institutions and represents one of the most important historical collections in North America (https://ucjeps.berkeley.edu/ina/pba/pba_main.html).

George F. Papenfuss succeeded Setchell as Curator of Algae and brought with him extensive collections from South Africa and Hawaii. He added collections from east Africa resulting from an expedition funded by the National Science Foundation in the 1960's. Papenfuss supervised 14 dissertations on the morphology and taxonomy of marine algae, maintaining UC's eminence in phycology. Paul C. Silva came to Berkeley in 1948 as a graduate student and returned as Curator of Algae in 1960. He collected extensively on the Pacific coast of North America.

UC has ~180,000 seaweed specimens with ~50,000 from California. The collections represent voucher material for regionally and internationally important studies and include approximately 2000 type specimens. With the recent addition of 40,000 specimens from the Los Angeles County Museum (including those formerly housed at the Allan Hancock Foundation) plus many gifts from orphaned collections, our holdings of California seaweeds are extraordinary.