A colleague, Ian Sussex, a senior research scientist at Yale, said others used Dr. Galston’s findings in the development of the more powerful defoliant, Agent Orange, named for the orange stripe painted around steel drums that contained it. The chemical, produced by Dow, Monsanto and other companies, is now known to have contained dioxins, long-lived compounds associated with cancers, birth defects and learning disabilities.  In the 1980s, Dr. Galston helped introduce popular courses in bioethics for undergraduates at Yale and in the 1990s was instrumental in founding the Interdisciplinary Center for Bioethics at the university. He explored the risks and rewards of genetically modified plants and crops, pesticides, stem-cell research, cloning and other issues as co-editor of two textbooks, “New Dimensions in Bioethics” (2000) and “Expanding Horizons in Bioethics” (2005).  In other important work in plant physiology, Dr. Galston experimented with the nutrient riboflavin and its role in enabling plants to absorb blue light, making a connection that he advanced and published in 1950 in the journal Science. He also wrote a book, “The Life of the Green Plant” (1961).  Arthur William Galston was born in Brooklyn. He graduated from Cornell and earned his doctorate in botany from Illinois in 1943.  After teaching at the California Institute of Technology, he moved to Yale in 1955 as a professor of plant physiology. At Yale, he was chairman of the department of botany in the 1960s and chairman of the department of biology in the 1980s. Dr. Galston was also a former director of the division of biological sciences at Yale. He retired in 1990 as a professor of botany emeritus.  Dr. Galston is survived by his wife of 66 years, Dale. He is also survived by a son, William, of Bethesda, Md.; a daughter, Beth, of Carlisle, Mass.; and a grandson.  In 2003, Dr. Galston reconsidered the arc of his research.  “You know,” he said, “nothing that you do in science is guaranteed to result in benefits for mankind. Any discovery, I believe, is morally neutral and it can be turned either to constructive ends or destructive ends.”  He concluded: “That’s not the fault of science.”  A version of this article appears in print on , on Page B6 of the New York edition with the headline: Arthur Galston, 88, Agent Orange Researcher, Dies. Order Reprints| Today's Paper|Subscribe
Mr. Galston did early research that helped lead to the herbicide Agent Orange, then helped raise awareness of the military’s use of it in Vietnam.