E. Yale Dawson's early passion for cacti continued into his professional career as a marine botanist studying seaweeds. He produced important floristic, taxonomic and biogeographic accounts of seaweeds, primarily in the N. E. Pacific. In 1963, the Botanical Society of America awarded him the Darbaker Prize for his magnum opus, The Marine Red Algae of Pacific Mexico, published in eight parts. Dawson also made many important observations on the distribution and abundance of cacti, collected and described several new taxa, and did much to enhance layperson interest in the biology and horticulture of these plants. For his contributions to the study of desert plants, the Cactus & Succulent Society of America made him a Fellow. He was also a member of the International Organization for Succulent Plant Study.