Otto Degener (1899–1988) was an American systematic botanist and naturalist known for his efforts in conservation. Degener was born in Orange, New Jersey, and received his undergraduate degree from the Massachusetts Agricultural College, later the University of Massachusetts-Amherst. In 1922, Degener received a Masters degree from the University of Hawaii, later pursuing a doctoral degree at the University of Massachusetts and Columbia University.

After visiting Hawaii as a tourist, Degener decided to live there, studying native Hawaiian plants. He collected specimens of 36,000 species, preserved approximately 900 threatened and endangered plants, and discovered a new tree in Fiji, the Degeneria vitiensis. After teaching at the University of Hawaii from 1925-1927, Degener became a naturalist for the Hawaii National Park.

In 1940, Otto Degener took the role of botanist on Anne Archbold’s Cheng Ho expedition in Melanesia. He purchased the boat from her in 1947 and started, with other stockholders, the Cheng Ho Trading and Exploring Company. On a trip to Tahiti, one of the partners registered the boat under his own name, which began a long legal battle. This collection contains a large number of the letters to and from Degener relating to this, clippings about the Cheng Ho and the people involved in the scandal, and legal papers.

In 1952, Degener met his wife, Isa Degener (1924–2018). While researching an unknown type of grass, Degener corresponded with an I. Hansen at the Berlin-Dahlen Garden in Germany. Upon visiting Germany, Degener sought to meet this I. Hansen in person, and noted that he was quite surprised when he found out that this individual was a woman. The two were married in 1953.

In addition to more than 400 publications throughout his career, Degener authored seven volumes of The New Illustrated Flora of the Hawaiian Islands (Honolulu, n.p.: 1932–?; HI call no. DS495 D319), Plants of Hawaii National Park (3rd ed., Ann Arbor: Braun-Brumfield, 1974 [1930]; HI call no., DS495 D319P 973), and Naturalist’s South Pacific Expedition: Fiji (Honolulu: Paradise of the Pacific, 1949; HI call no., MB D317N). Degener noted that a total of nine books published should be accredited to himself and his “helpmate” and wife Isa Degener, with whom he worked throughout his career. Flora Hawaiiensis is said to have been the most comprehensive published documentation of plant life on the island of Hawaii. In addition to research findings related to plants, Degener also examined lore, customs and local history throughout his works. For his accomplishments, Degener was honored with the Linnaeus Medal (1962), the New York Botanical Garden Service Award (1973), and the Wildenow Medal from the Berlin Botanical Garden (1979). In 1979, the State Senate of Hawaii also voted to commend him for his conservation work.